Widespread 5–15cm of Fresh Snow to Blanket the Southern Prairies Early This Week

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As we get closer to the start of the storm expected to cross the Prairies and weather models have come closer in agreement, we now have more confidence to discuss the potential impacts over the next couple of days. This storm will travel eastward along the international border, which will limit most of the snowfall to southern portions of all three Prairie provinces.

Alberta

The snow will make its way into Southwestern Alberta after midnight, gradually spreading eastward across the province during the early and mid-morning hours. It’s during this time that there is also a risk of freezing rain for communities closer to the border, but it will quickly be replaced by snow. Meanwhile the scattered flurries remaining from Sunday through Calgary to Red Deer are also expected to organize and intensify, joining the snow further to the south.

The rdps model showing precipitation type and intensity at 7am MT on Monday, courtesy of WeatherBell.

As we get later in the morning, there will likely be some intensification and increased snowfall rates along the Highway 3 corridor and southward, which will result in greater overall accumulation. By lunchtime, the snow will begin to taper off to the north of Calgary and then from west to east starting in the early afternoon and exiting the province completely in the evening.

A widespread 5-15cm of snow is predicted by the end of Monday across Southern Alberta and areas that experience the heavier snowfall closer to the border could be on the higher end of that range. There could be pockets where accumulation totals could approach 20cm to the south of Highway 3, but this is much more likely to occur east of Highway 36.

The rdps model showing precipitation type and intensity at 7pm CT on Monday, courtesy of WeatherBell.

Saskatchewan

The leading edge of the snow will move into Southwest Saskatchewan in the mid-morning and it will spread eastward across the province through the day. There is also the slight risk for some freezing rain along the border to the south of Maple Creek and Shaunavon, but it should be over quickly.

The snowfall across Saskatchewan will be fairly short-lived and by the time the snow reaches the Manitoba border in the evening, it will actually start to taper off back along the Alberta border. Throughout the remainder of the evening, overnight and into Tuesday morning, the snow will gradually end from west to east.

Similarly to in Alberta, much of Southern Saskatchewan can expect at least 5cm of snow by midday Tuesday. There will also be heavier snowfall from Maple Creek to Estevan, mostly along Highway 13 and southward. This particular region will likely see snowfall totals around 20cm and Environment Canada may issue a snowfall warning to reflect this.

The rdps model showing precipitation type and intensity at 7am CT on Monday, courtesy of WeatherBell.

Manitoba

By the time the snow makes its way into Manitoba Monday evening, the entire system is expected to shift course and start moving more in a southeast direction as it interacts with another low pressure system from the States. As a result, the steady moderate snowfall will not extend as far east through the province. Regardless, the snow will still make its way across Southern Manitoba overnight and into Tuesday morning. It will slowly start to taper off from west to east around sunrise, gradually ending for border communities in the Eastman Region Tuesday evening.

The system will also start to weaken as it makes its way into Manitoba, so the heavier snowfall expected in both Alberta and Saskatchewan is looking like it won’t be as much of a concern. There will still be a swath of the region that can expect more than 5cm of snow by the end of Tuesday, but it is likely that this won’t exceed 10cm.

It is possible that this change in direction is more subtle than showing on weather models or doesn’t occur at all. We will watch as the system takes shape and makes its way through Alberta and Saskatchewan. If it appears that the track will change from what was initially expected, it’s likely that we will update our forecast for Manitoba.

As it stands, a decent amount of snow is expected to fall across the Southern Prairies. This snow will be heavy in some areas, which will likely make travel a headache, especially on some of the busier highways. Be sure to give yourself plenty of extra time if travelling during these periods of heavy snowfall and stay safe.

Snow Squalls Take Aim at London, Barrie and Northern GTA on Sunday With Up to 25-50cm of Snow Possible

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We enjoyed a brief break from the wintry weather on Saturday as temperatures soared into the double digits across much of Southern Ontario. The exception was Eastern Ontario, where the Ottawa Valley dealt with hours of freezing rain.

But that warm spell is going to be short-lived. Cooler air returns overnight into Sunday, and temperatures will slide back below the freezing mark. Once that happens, the lake effect snow machine will fire up again for the next couple of days.

And no, it isn’t déjà vu. The target zone for this round of squalls will look very similar to last week’s event, but the focus shifts slightly east. That puts areas like London, Barrie and even the Northern GTA, including York Region, in line to be hit hard.

By the time the squalls wind down on Monday, the hardest hit spots could be digging out from more than 25cm, with the potential for very localized pockets of 50cm.

PRECIP TYPE - MAP FROM WEATHERBELL

We expect the snow squall activity to begin ramping up late Sunday morning. As temperatures fall, lake effect rain bands will flip over to snow off the southeast shoreline of Lake Huron and Georgian Bay.

While the changeover happens in the morning, ground temperatures may stay just above freezing for several hours. This means the first few hours of snow could melt on contact. Accumulation will start later in the day once temperatures reach the freezing mark.

Even before the snow begins to stick, visibility will drop quickly. Those in the affected areas should expect sudden whiteouts and dangerous driving conditions.

Hourly snowfall rate (cm) - MAP FROM WEATHERBELL

By the dinner hour, the squalls will become much more organized. Snowfall rates from the Lake Huron band could rise to 5cm per hour. This main band is expected to extend from Lake Huron through Goderich and southern Huron County into the London region.

Additional squall activity will form southeast of Georgian Bay, running from the shoreline through Barrie and Angus and into Newmarket and Durham. This band looks weaker than the Lake Huron squall at first, but could still deliver rates of 2 to 4cm per hour.

Hourly snowfall rate (cm) - MAP FROM WEATHERBELL

The worst conditions are likely around midnight. The Lake Huron band is expected to lock onto London, bringing intense snow and rapid accumulation of 6 to 8cm per hour.

The Georgian Bay squall will also strengthen, sliding south of Barrie and focusing on Angus, Bradford and Newmarket. Some signals show it reaching into the Eastern GTA, including Scarborough, Ajax and Oshawa.

These squalls should remain mostly stationary overnight, although minor drifting is possible. As temperatures fall several degrees below freezing, expect snow to pile up quickly.

Hourly snowfall rate (cm) - MAP FROM WEATHERBELL

By mid-morning Monday, the bands will begin to weaken as winds shift more westerly. Some lake effect flurries could linger east of Lake Huron into Grey Bruce, but they are not expected to be very organized. Everything should taper off by late Monday.

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Snow squall forecasting always comes with big caveats. The bands are extremely narrow, which means the difference between 50cm and almost nothing can be only a few dozen kilometres.

This is why we provide a broad range. They help capture that uncertainty, but they are not a guarantee. With this event, the bands appear very intense but also very narrow, which means gradients will be sharp.

Based on the latest data, we expect the hardest hit areas from the Lake Huron squall to include Goderich, Clinton, Lucan, Exeter, Mitchell and London. Snowfall totals here could range from 25 to 50cm, with the chance that someone ends up over 50cm in a very localized spot.

Surrounding regions, including Grand Bend, Tillsonburg, Stratford, Wingham, and Point Clark, could see 15 to 25cm.

Further east into Grey Bruce and Dufferin County, we are expecting 5 to 15cm mainly on Monday as the lake effect shifts northward.

The Georgian Bay band looks even narrower than the Lake Huron band. A small corridor stretching from Collingwood through Angus and into Innisfil could see 25 to 35cm, with a chance of 50cm if the band really intensifies.

The City of Barrie is right on the edge. A small shift north or south would bring very different results. For now, the highest totals look likely in the south end of the city with 15 to 30cm. The north end may be closer to 10 to 20cm.

Substantial totals may also extend into the Northern GTA, including Bradford, Newmarket and Aurora. Totals along the Highway 400 and 404 corridor could range from 15 to 30cm.

Across the east end of Toronto and Durham, including Ajax, Pickering and Oshawa, occasional heavy bursts may bring 5 to 10cm.

The rest of Southern Ontario should see less than 5cm of snow by Monday from the lake effect.

Snow Squalls Could Bury Parts of Southern Ontario’s Snowbelt in Up to 50cm of Snow Early This Week

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As much of Southern Ontario cleans up after our first widespread snowfall of the season, Mother Nature is showing no signs of slowing down. The lake effect snow machine is roaring to life over Lake Huron and Georgian Bay as we kick off the second week of November.

Snow squalls have already developed south of Lake Huron late Sunday evening and are expected to strengthen through the night. We’re also anticipating some squall development along the southern shoreline of Georgian Bay, which should organize by Monday afternoon or evening.

Two main regions are likely to see the most intense activity. The first stretches between Sarnia and London, while the second includes areas south of Georgian Bay from Blue Mountain and Meaford toward the west of Barrie. Both zones could see heavy snow squalls lasting through to Tuesday morning.

While snowfall totals will vary significantly across short distances, confidence is increasing that the hardest hit areas could see as much as 25 to 50cm by the time the squalls taper off on Tuesday. Localized pockets may even exceed 50cm, depending on where the heaviest bands set up.

Road conditions are expected to deteriorate quickly in these regions, with road and highway closures likely late Monday and into early Tuesday when the most intense squalls occur. Travel should be avoided unless absolutely necessary, as these bands can produce sudden whiteouts, making it nearly impossible to see the road ahead.

ESTIMATED AIR TEMPS AROUND 1.5KM ABOVE GROUND - MAP FROM WEATHERBELL

This setup is being fueled by a rare November appearance of a mini “Polar Vortex” which is pulling a blast of Arctic air into Southern Ontario. This cold air is flooding the upper levels of the atmosphere and setting the stage for intense lake effect activity.

To put it simply, when forecasters talk about 850mb temperatures, we’re referring to the air temperature roughly 1.5 kilometres above the ground. This level helps forecasters understand how cold the air mass is higher up in the atmosphere, which is critical for predicting lake effect snow.

Over the next few days, 850mb temperatures are expected to plunge into the negative teens. Lake effect snow forms when there’s a large temperature difference between the lake surface and the air above it, generally 13°C or greater. With upper air temperatures between -10°C and -15°C and lake temperatures still above 10°C, that difference is more than 20°C, creating ideal conditions for lake effect snow to thrive.

hourly snowfall rates (cm) - MAP FROM WEATHERBELL

As of midnight, snow has already developed off the southern shores of Lake Huron, impacting the Sarnia region. So far, the bands have been disorganized and spread out, but that’s expected to change by late Monday morning as a stronger, more focused squall forms somewhere between London and Sarnia.

While the exact placement remains uncertain, areas near Petrolia and Strathroy appear most likely to be in the direct path. The band will likely shift through the day as wind directions fluctuate, leading to varying snow intensities across nearby towns.

hourly snowfall rates (cm) - MAP FROM WEATHERBELL

By Monday evening, things will really start to ramp up. The main squall off Lake Huron will likely push inland, with a more northwesterly wind direction steering it toward Grand Bend, Goderich and potentially the western edges of London. It’s still unclear if the squall will reach directly into London or remain just outside the city, but if it does, the heaviest snowfall will likely fall on the west side.

Meanwhile, snow squalls are expected to organize over Georgian Bay with heavy snow bands developing between Owen Sound and Barrie. There’s still some disagreement among models, with some focusing more on Wasaga Beach and Barrie while others favour a southern shoreline setup.

An interesting twist could occur if these Georgian Bay bands extend far enough inland to be enhanced by Lake Ontario. In that case, snow could reach into the western GTA and even the Niagara region, leading to sudden bursts of heavy snow if everything aligns.

hourly snowfall rates (cm) - MAP FROM WEATHERBELL

This lake effect activity is expected to persist overnight and into Tuesday morning, though the Georgian Bay bands should weaken slightly around sunrise. West of London, however, heavy snow could continue well into Tuesday morning before breaking apart as conditions become less favourable later in the day.

As always with lake effect snow, totals are extremely difficult to pinpoint. These narrow bands can stay locked over one community for hours while completely missing another just a few kilometres away. One person may end up shovelling half a metre of snow while someone nearby barely sees a dusting.

That said, two areas consistently stand out across the latest model runs. One includes Lambton Shores, Grand Bend and Strathroy, while the other covers the southern Georgian Bay shoreline and higher terrain around Blue Mountain. These regions could see totals ranging from 25 to 50cm by Tuesday.

Surrounding communities such as Petrolia, Thamesville, St. Thomas and Lucan, along with Orangeville, Shelburne and Flesherton, are more likely to see 15 to 25cm.

Both London and Barrie sit right on the edge between lighter and heavier accumulations. We currently have them in the 5 to 15cm or 15 to 25cm zones, depending on how far east the snow squalls extend.

Finally, the Niagara region remains uncertain. If the Georgian Bay squalls stretch far enough inland and connect with Lake Ontario, parts of the region could pick up over 15cm of additional snow.

Outside of these snowbelt regions, impacts will be much less significant. A few flurries and brief bursts of snow are possible as the squalls wobble, but most areas outside the direct lake effect zones should remain relatively calm through Tuesday.

Snowy Sunday Sweeps Into Southern Ontario With First Widespread Snowfall of the Season

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While there has been a lot of uncertainty surrounding Southern Ontario’s first widespread snowfall event of the season, we’re finally starting to get a clearer picture of what will unfold on Sunday. After several model shifts over the past few days, the latest data is now coming into better alignment, giving us a more confident idea of how this system will behave.

A developing low-pressure system is expected to move in from the southwest late Saturday night, tracking across areas near Lake Erie through the day on Sunday. As it does, it will bring a broad swath of snow stretching from Windsor through the Golden Horseshoe and into Eastern Ontario. Snow is expected to last much of the day before gradually tapering off overnight.

At this stage, snowfall totals are expected to vary quite a bit across the region. The exact placement of the heaviest snow bands remains uncertain, and surface conditions will also play a big role. Since the ground is still relatively warm, some of the early snowfall may melt on contact before it can begin to accumulate, especially on roads and sidewalks.

In general, by Monday morning, snowfall totals are expected to range from around 5 to 10 cm across the Golden Horseshoe and into Eastern Ontario. Within those areas, localized pockets, particularly in Eastern Ontario, could pick up as much as 15 to 20 cm according to the latest model runs. Further north and west, across Central and Southwestern Ontario, amounts will be lower with less than 5 cm expected in most spots.

As the system departs, colder air will pour into Southern Ontario late Sunday night, sending temperatures well below freezing. Any slushy snow or water on roads, sidewalks, and driveways will freeze quickly overnight, which could create slick conditions for the Monday morning commute. Drivers should be prepared for icy patches, and there’s a decent chance of school bus cancellations in areas that see higher snowfall totals.

The colder air will also fire up the lake effect snow machine early next week. Model guidance suggests that an intense but narrow band of snow could form southeast of Lake Huron late Monday and continue into Tuesday. This could impact communities such as Grand Bend and London, where local snowfall totals could exceed 25 cm if the band remains stationary for an extended period.

PRECIP TYPE - MAP FROM WEATHERBELL

For timing, snow is expected to begin in Deep Southwestern Ontario shortly after midnight. Around Windsor and Chatham, it may even start as rain before transitioning to snow as temperatures drop closer to dawn.

PRECIP TYPE - MAP FROM WEATHERBELL

By late Sunday morning, the snow will have spread into the Golden Horseshoe, becoming heavier through the afternoon. In Eastern Ontario, snow will likely begin around Kingston early in the morning and reach the Ottawa area by midday.

hourly snowfall rates (cm) - MAP FROM WEATHERBELL

The heaviest snowfall rates across the Golden Horseshoe are expected from early to mid-afternoon, with some models projecting bursts of 2 to 4 cm per hour at times before tapering off toward the evening.

PRECIP TYPE - MAP FROM WEATHERBELL

For Eastern Ontario, steady snow will continue through the afternoon, peaking after dinner before easing into scattered flurries overnight. With that timing, school bus cancellations are quite possible for parts of Eastern Ontario on Monday.

There are also some indications that freezing rain or ice pellets may mix in along the international border Sunday evening. Areas such as Kingston, Brockville, and Cornwall are most at risk for this brief mix, which could add an extra layer of slickness to untreated surfaces.

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While there is still some disagreement among the models on exactly where the heaviest snow will fall, the general expectation remains 5 to 10 cm along the Golden Horseshoe and into Eastern Ontario, with some locally higher amounts near 15 cm.

We’ve outlined portions of Eastern Ontario and the higher elevations of the Niagara region on our map with a dotted zone, representing areas that could overachieve and see closer to 20 cm. However, that outcome is far from certain.

Keep in mind that this is the first significant snowfall of the season, and with ground temperatures still above freezing, actual accumulation could vary from one street to the next. Some areas may see a quick coating, while others struggle to hold the snow through the day, especially near the lakeshores.

Elsewhere, Southwestern Ontario and much of Central Ontario should see lighter amounts, generally only a few centimetres, with some localized areas possibly reaching up to 8 cm. Regions like Grey-Bruce and the northern parts of Central Ontario will likely miss out on the heaviest snow this time, but that may not last long as lake effect activity ramps up early next week.

PRECIP TYPE - MAP FROM WEATHERBELL

As higher-resolution models continue to come into range, we’re getting a clearer idea of what the first snow squall event of the season could look like. Current projections suggest activity will develop on Monday, with a more organized squall forming by the evening.

This band may set up somewhere between Grand Bend and Kettle Point, extending inland, likely just west of the City of London. Additional bands may also develop off Georgian Bay, impacting areas around Meaford and Collingwood.

Communities caught under these narrow squalls could see impressive snowfall totals, while just a few kilometers away, grass may still be visible. We’ll continue to refine the details as the event approaches and will have a more specific forecast on who could see the most snow closer to Monday.

Overall, this marks the true start of the winter season across Southern Ontario, with several systems and lake effect events lining up behind this one. It’s a good time to check that your winter tires are ready, snow shovels are handy, and morning routines include a few extra minutes to clear off your car. Winter is here to stay.

Southern Ontario to Plunge Into Winter as Sunday Snowstorm Could Dump Up to 20 cm of Snow

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It feels like just yesterday we were talking about record-breaking heat that stretched well into October. But November has been a completely different story, with winter now making its presence known across Southern Ontario. Those warm late-autumn days are coming back to haunt us, as the still-warm lakes are setting the stage for a series of snowy chances in the days ahead, including the lake effect snow machine coming to life.

Cold Arctic air is set to flood into the province, bringing several snowmakers with it, including a potential snowstorm on Sunday, followed by intense snow squalls early next week.

Our first system arrives on Friday, spreading across Ontario throughout the day. Southern Ontario will mainly see rain from this one, while Northern Ontario braces for a significant dumping of snow. Some areas could see close to 20 cm by Saturday.

As colder air rushes in behind this system, temperatures will plunge across Southern Ontario through Saturday night. By Sunday, much of the region will be below freezing, setting the stage for the next system expected to move in during the day Sunday. Early indications suggest that parts of Southern Ontario could see significant snowfall from this system, with totals possibly reaching up to 20 cm by Sunday night.

That said, there’s still plenty of uncertainty surrounding the exact track of the storm. A slightly more southern route could pull the heaviest snow into the Greater Toronto Area as colder air dips farther south.

PRECIP TYPE - MAP FROM WEATHERBELL

The first round of precipitation will begin in Northwestern Ontario late Thursday, spreading across Northeastern and Southern Ontario by Friday morning.

RAINFALL TOTALS - MAP FROM WEATHERBELL

For most of Southern Ontario, this will mean a steady rainfall, with totals around 5 to 10 mm, although localized pockets near the lakes could see closer to 15 mm.

SNOWFALL TOTALS - MAP FROM WEATHERBELL

Higher elevations in Central Ontario, including Algonquin Park, could see some wet flurries mix in at times. Farther north, around Hearst, Kapuskasing, Cochrane, and Timmins, it’s all snow, with totals of 15 to 20 cm possible by Saturday morning.

TEMPS - MAP FROM WEATHERBELL

Behind the system, much colder air will spill into Central Ontario overnight Friday into Saturday, dropping temperatures well below freezing. The rest of Southern Ontario will see the chill arrive soon after, with most regions seeing their daytime highs recorded just after midnight Saturday before temperatures tumble through the day.

TEMPS - MAP FROM WEATHERBELL

By early Sunday morning, the cold will be firmly in place. Most areas will be below freezing, except for parts of Deep Southwestern Ontario and along the Lake Ontario shoreline where temperatures will hover just above zero.

PRECIP TYPE - MAP FROM WEATHERBELL

This cold setup will pave the way for Sunday’s incoming system. Models are in disagreement about the storm’s path, which will ultimately decide who gets the heaviest snow. The American and Canadian models track the low across Lake Erie and Lake Ontario, placing the rain-snow line near the GTA.

In this scenario, areas north of the GTA, including parts of Southwestern Ontario, Lake Simcoe, and the Ottawa Valley, would see heavy snow, while the GTA experiences a mix of rain, ice pellets, and wet snow.

PRECIP TYPE - MAP FROM WEATHERBELL

Even a small shift southward, as suggested by the European model, would change everything. That track takes the low through Pennsylvania and Upstate New York, shifting the heaviest snowfall into the GTA and surrounding regions, with totals over 15 cm.

SNOWFALL TOTALS - MAP FROM WEATHERBELL

In this case, the snow would stretch from London through the GTA, Peterborough, and into Ottawa, while Central Ontario and Grey-Bruce see lower amounts.

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For now, most models favour the northern track, so that’s what we’re leaning toward in our preliminary forecast. But if the European solution proves right, those snowfall zones could shift south before the final forecast is issued.

Under the current setup, the heaviest snow is expected across a broad stretch of Southwestern Ontario, including the Lake Huron shoreline through Kitchener and up toward Barrie, Lindsay, and Peterborough, extending into the Ottawa Valley. These areas could see 10 to 15 cm of snow, with localized pockets near 20 cm possible.

The American NAM model is even more aggressive, suggesting up to 30 cm in some areas, though that’s likely overdone. The London area, GTA, and Eastern Ontario fall into a mixing zone, with 5 to 10 cm possible once precipitation switches to snow. Should the system shift farther south, those totals could increase.

Farther south, places like Windsor, Chatham, Sarnia, and the Niagara Region are expected to stay mostly rain, though a slushy 5 cm of snow is possible.

Snowfall will taper off by late Sunday, but the story won’t end there. Behind the storm, a strong surge of cold air over the still-warm Great Lakes will ignite a burst of lake-effect snow squalls on Monday.

The exact regions that will see the most intense squalls remain uncertain until higher-resolution models come into range, but areas downwind of Lake Huron and Georgian Bay should prepare for the potential of significant accumulations. Some communities could be digging out from 25 cm or more by early next week.

Snowy Scare: Frightful Flurries May Haunt Parts of Southern Ontario on Halloween Night

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After a soggy start to Halloween Eve across Southern Ontario on Thursday, a strong system will cast a gloomy spell over the region with widespread rainfall. But don’t be fooled, as that’s only a taste of what Mother Nature has brewing in her cauldron for Halloween itself.

Last year, we were treated to a mild and friendly Halloween with temperatures that felt more like a trick than a treat. This year, however, it looks like Halloween will send a real shiver down your spine as temperatures drop to levels more fitting for the undead.

Rain from Thursday is expected to linger overnight and into the early hours of Friday, heavy at times, especially across Eastern Ontario. The good news is that the worst of the rainfall should clear out just in time for trick-or-treating across Southwestern Ontario and the Golden Horseshoe. Temperatures will hover around what’s normal for this time of year, ranging from the mid to upper single digits, possibly reaching the low double digits in Deep Southwestern Ontario.

But it’s as if a witch has placed a chilling curse over Central and Eastern Ontario. As the rain lingers through Friday, some areas could begin to see strange white shapes drifting through the sky and no, they aren’t ghosts! These spooky apparitions are far more real, as rain could turn to wet flurries as early as Friday afternoon. Cold air will creep in like a Halloween fog, sending temperatures tumbling toward the freezing mark by evening.

While there’s some disagreement between models (a classic case of meteorological mischief), there’s solid agreement that a wide stretch of Central Ontario may experience at least a few wet flurries on Halloween night.

Where the models differ is in timing and intensity. Some are quite aggressive, conjuring an earlier and more widespread switchover to snow that could even allow for light accumulations in higher elevations. Others show a less frightful outcome, with flurries limited to the hills and highlands later in the day as the rain fizzles out elsewhere.

PRECIP TYPE - MAP FROM WEATHERBELL

As we rise on Halloween morning, rain will still be haunting much of Southern Ontario, though it will begin to taper off from west to east.

That’s where the great model split begins. For this forecast, we’re focusing on the NAM (American) and HRDPS (Canadian) models, which represent two distinct camps. The European model seems to be siding with the Canadian solution.

The American model pulls colder air into Central Ontario faster, dropping temperatures a few degrees lower than the Canadian model. It might not sound like much, but when temperatures hover near freezing, every degree counts. This could allow snow to start mixing in by early afternoon.

Areas like Algonquin Park, Haliburton, Bancroft, and northern Muskoka may see the first flurries, with the “mixing zone” spreading south through the afternoon into Muskoka, northern Simcoe County, and the Kawartha Lakes region.

PRECIP TYPE - MAP FROM WEATHERBELL

The Canadian model delays the switchover until closer to dinnertime, mainly over higher elevations.

By then, the precipitation in western areas may already be fading, keeping Muskoka and Simcoe County mostly rain-soaked rather than snow-covered.

PRECIP TYPE - MAP FROM WEATHERBELL

If the American model’s spookier version plays out, several hours of heavy, wet snow could fall Friday evening. While the ground is still warm, we’ve seen before that a strong enough burst of snow can briefly overcome that warmth and start to accumulate.

This model also spreads the snowy risk zone further east, even hinting at flakes creeping into the Ottawa Valley.

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The most likely areas to see actual snow include the higher elevations of Central Ontario, such as Sundridge, Huntsville, Algonquin Park, and Bancroft. These regions could even pick up a few slushy centimetres by night’s end if the stronger scenario comes true.

Elsewhere across Central Ontario, including Parry Sound, Bracebridge, Orillia, Kawartha Lakes, Tweed, and Pembroke, some wet flakes could mix in as trick-or-treaters prowl the streets. Accumulation isn’t expected here as the ground remains too warm, but it might add an extra eerie touch to the evening.

ESTIMATED PRECIP OVER LAST 3 HOURS - MAP FROM WEATHERBELL

As the ghosts, goblins, and ghouls hit the streets after nightfall, Southwestern Ontario will enjoy the calmest conditions, with rain clearing out hours earlier.

Central and Eastern Ontario, however, may not be as lucky. Light rain or even a few flurries could continue into the early evening, adding some spooky atmosphere to the night.

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For the prime trick-or-treating hours, Deep Southwestern Ontario will be the mildest, with temperatures around 8 to 12°C at 8 PM. Elsewhere across the Golden Horseshoe and Eastern Ontario, temperatures will settle into the mid to upper single digits.

The chilliest readings will haunt Central Ontario, where places like Muskoka, Algonquin Park, and Bancroft may see readings near the freezing mark with flakes swirling through the air. Those heading out should make sure their costumes have a few extra layers because this Halloween, it’s not just the monsters giving people chills.

Have a Happy Halloween!

Southern Ontario Turns Chilly With a Chance of Early Season Flurries for Some Areas Friday Morning

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The feeling of change is definitely in the air across Southern Ontario this week. Fall colours are now past their peak in many areas, and a noticeable chill has taken hold across the region. The arrival of cooler air, combined with the still-warm Great Lakes, has kicked off another round of lake-effect precipitation off Lakes Erie, Ontario and Huron.

While it’s still warm enough to keep most of that precipitation as rain, the traditional “snow belt” east of Lake Huron and Georgian Bay will continue to see periods of lake-effect rain through Thursday and into Friday. Local rainfall totals of 25 to 50 mm are possible by Friday, especially east of Lake Huron.

However, not everyone will escape a touch of wintry weather this week. The latest model data suggests that temperatures could dip close to the freezing mark across parts of Central Ontario late Thursday night into early Friday morning. With some lingering showers still moving through the region, a few areas could see those showers briefly mix with wet flurries before sunrise on Friday.

The best chance to spot the first flakes of the season will be across Northern Muskoka (including Huntsville and Sundridge), Algonquin Park, Bancroft and North Bay. That said, precipitation will be very scattered, and not all of these locations will see snow. Even if flakes do fall, they won’t stick around for long as the ground remains too warm and temperatures will quickly climb above freezing later in the morning.

ESTIMATED TOTAL RAINFALL BY FRIDAY - MAP FROM WEATHERBELL

For those near Lake Huron and Georgian Bay, Thursday looks to be a wet one. Bands of lake-effect rain are expected to develop overnight Wednesday and linger through the day Thursday. As is typical with lake-effect events, rainfall totals will vary greatly over short distances depending on where the bands set up.

These bands are expected to wobble around through Thursday into Friday, spreading precipitation over a broader area rather than locking in on one spot. If one of the stronger bands does remain stationary for an extended time, localized flooding could occur, particularly near Kincardine and Goderich where some models show up to 50 mm of rainfall possible by Friday.

The lake-effect setup off Georgian Bay isn’t expected to be quite as strong, but parts of Simcoe County around Collingwood, Wasaga Beach and Barrie could still see locally up to 25 to 50 mm of rain. Again, the highest amounts will be very localized.

Elsewhere across Southern Ontario, expect occasional showers Thursday with generally less than 10 mm of rain as the heaviest precipitation remains confined to areas near the lakeshores.

By Friday morning, precipitation will gradually taper off as conditions become less favourable for lake-effect activity.

ESTIMATED AIR TEMPERATURE on friday morning - MAP FROM WEATHERBELL

Overnight Thursday into Friday, temperatures will drop into the low single digits across much of Southern Ontario, with some Central Ontario communities dipping to near or just below freezing.

PRECIP TYPE - MAP FROM WEATHERBELL

While it’s not the first time this fall that temperatures have touched the freezing mark, what’s different this time is that lingering precipitation from both the lake-effect activity and a system over Quebec could overlap with those cold temperatures.

If any precipitation develops overnight, it could easily fall as wet flurries given the near-freezing surface temperatures and even colder air aloft that would favour snow instead of rain.

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It’s worth noting that models disagree on how much precipitation will actually be present on Friday morning. Some may be underestimating light, scattered precipitation, which means there’s a chance flakes could be seen as far south as Huntsville and Bancroft. The most likely region for these flurries remains around North Bay and Algonquin Park, where multiple models consistently show light snow.

Unless you’re up early Friday morning, you’ll likely miss the brief appearance of the season’s first flakes. Any snow that does fall will melt quickly once temperatures climb above freezing, and no travel impacts are expected.

STORMY SUNDAY: Parts of Ontario Could Experience Damaging Wind Gusts & Flooding Risk This Weekend

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Environment Canada has released its latest medium range forecast, highlighting the potential for 70-90km/h damaging wind gusts across Southwestern Ontario, the Niagara regions and western GTHA regions on Sunday, October 19th, 2025.

They also mention a rainfall risk for Northeastern Ontario with the potential for 30-60mm of accumulation that could cause isolated flooding.

If this trend continues towards the weekend, it’s certainly possible that the ‘minor’ risk will be increased to a ‘moderate’ risk but seeing as we’re still four days out, it makes sense that Environment Canada is keeping the risk at the minor level.

Environment Canada does have a specific explanation for minor risks and it is: “This weather event is potentially significant or of interest. Users should stay informed.”

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💨 Southern Ontario

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Environment Canada writes in their forecast for Southern Ontario:

“Strong southwesterly winds with gusts of 70 to 90 km/h are likely for areas near Lake Erie and portions of southwestern Ontario. Winds will shift to northwesterly with the passage of a cold front late in the day, with gusts up to 90 km/h possible. Confidence is low regarding the timing and strength of winds expected.”

They also break down the risks:

Hazard(s): Wind

Location: Southwestern Ontario and western portions of the Greater Golden Horseshoe.

Timing: Sunday

Impact(s): Broken tree branches and downed trees. Power outages likely.

Confidence: Low (1 out of 4)

Impact: Moderate (2 out of 4)

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🌧️Northeastern Ontario

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Here are Environment Canada’s details for the rainfall risk in Northeastern Ontario:

”Significant rainfall is expected, with rainfall amounts of 30 to 60 mm likely. Confidence is low regarding the exact location of heaviest rainfall at this time.”

They also break down the risks:

Hazard(s): Rain

Location: Portions of northeastern Ontario.

Timing: Sunday

Impact(s): Possible flooding in low-lying areas.

Confidence: Low (1 out of 4)

Impact: Moderate (2 out of 4)

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🔎 Staying Safe and Prepared

As we move towards the winter months, it’s critical to stay informed! To keep a close eye on our latest forecasts and get notified of any alerts, download our free app Instant Weather, available on Apple and Android devices.

Take a moment to secure any loose outdoor items before the storms arrive. Things like patio furniture, trampolines, and garbage cans can become projectiles in strong winds.

If you're planning to be on the roads, be prepared for challenging driving conditions such as sudden downpours, significantly reduced visibility, and the possibility of water pooling on roadways, especially in areas expecting heavier rainfall.

Stay safe everyone and if it’s safe to do so, share your reports with half a million community members on our Facebook group called Ontario Storm Reports!

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Disclaimer: These forecasts are issued by Environment Canada and typically published via their Twitter/X accounts. We receive these forecast via a daily email and often publish them to help inform our communities.

Get Your Shovels Ready: Ontario's Snowbelt Could Be Buried Again This Winter

Satellite image from GOES-16 shows lake effect snow coming off the Great Lakes on February 29th, 2024. Courtesy of CSU/CIRA & NOAA.

The summer of 2025 was a hot one in Southern Ontario, in which we saw high temperature records consistently broken throughout the region. This trend has continued into October, with temperatures surpassing 30°C in parts of Southwestern and Eastern Ontario during the first weekend of the month.

Despite the fact that we’re gradually moving into the coldest part of the year, the heat from the summer and fall will continue to impact local weather conditions this winter. This will be particularly evident as lake effect snow, a phenomenon that occurs every year in the late fall and early winter in Southern Ontario.

The two main ingredients necessary for the development of lake effect snow are a large unfrozen body of water and a very cold air mass. The air mass needs to be at least 13°C colder at the 850mb pressure level of the atmosphere (this is typically found at around 1500 metres) than the temperature of the surface of the water. Once this threshold is reached, it’s like a switch being flipped and the lake effect snow machine starts.

There is more to the development of lake effect snow than just cold air and an open body of water. Another key component in lake effect snow development is moisture. Ideally, the relative humidity at the surface needs to be at least 80% for lake effect snow to form and levels below 70% could actually inhibit development. It can usually be assumed that the lake itself can provide enough moisture, but this is not always true. There also needs to be limited wind shear with height between the surface and the 700mb pressure level so that the moisture is more focused, sort of like a hose. The strongest, most organized bands of lake effect snow develop when the wind shear is less than 30°.

Finally is the concept known as “fetch”, which is the distance that the air mass travels over the lake. Fetch needs to be at least 100km in order for lake effect snow to develop and the greater the fetch, the more snow is produced. When considering prevailing wind directions, the traditional snowbelts are found in areas that are downwind of the greatest possible fetch over the Great Lakes, i.e. Buffalo and the entire length of Lake Erie.

The creation of lake Effect Snow. Courtesy of Environment Canada.

As the cold air mass travels over the much warmer surface of the lake, the warmth and moisture from the surface is transferred into the lower atmosphere. The warmer, moister air rises and it eventually cools and condenses, forming narrow bands of clouds. These clouds continue to travel over the open lake, gathering even more moisture, until they eventually reach land and the snow starts to fall at rates that can easily exceed 5cm per hour and could even be as high as 20cm per hour! It’s important to note that the hardest hit areas are actually not found immediately at the shoreline, but rather 30-50km inland from the lake.

The direction of the winds dictates which areas are hit by the lake effect snow so as long as the ideal conditions continue, so too will the development and subsequent falling of lake effect snow. This could lead to several days of heavy snow hitting the same area while there are sunny skies less than 20km away. A slight shift in wind direction can quickly change which area gets hit and that makes lake effect snow notoriously tough to forecast. In Southern Ontario, lake effect snow typically hits areas to the east of Lake Huron and Georgian Bay, but it can also impact communities to the north of both Lake Erie and Lake Ontario.

Surface Temperature of Lake Huron throughout 2025 plotted with the 30 year average. Courtesy of NOAA CoastWatch.

So how does a hotter-than-average summer impact lake effect snow? To put it simply, a warmer summer leads to warmer lakes. Looking at Lake Huron, the main source of lake effect snow in Southern Ontario, the surface water temperature is approximately 2°C warmer than the 30 year average.

One of the important properties of water is its high heat capacity, which means that lakes heat and cool slower than the surrounding land. The warmer lakes will take longer to freeze, meaning that the lake effect snow machine can run even longer.

The current surface temperatures across the Great Lakes are very similar to last year at the same time. Many will remember last fall when the Muskoka Region was buried after several days of intense lake effect snow, trapping people in their homes and cars after the highways were closed.

This trend continued through most of the winter due to large expanses of open water remaining present in the Lakes. This was particularly the case in Bruce, Grey, and Huron Counties, where consistent lake effect snow resulted in massive snow piles and drifts that were up to 12 feet tall! The amount of snow also had an effect on local schools, with more than 30 snow days announced for students of some school boards.

Surface temperatures of the Great Lakes as of October 7th, 2025. Courtesy of Noaa Coastwatch.

Surface temperatures of the Great Lakes as of October 6th, 2024. Courtesy of NOAA Coastwatch.

While it is still too early to predict exactly how much snow will fall and where over the coming months, it is looking likely that we can expect a considerable amount of lake effect snow like last year.

💨 WINDY WEDNESDAY: Environment Canada Forecasting Severe Thunderstorms With 90km/h Wind Gusts, Toonie Sized Hail & 50mm Flooding

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Environment Canada has released its latest Thunderstorm Outlook forecasting a “moderate” (2 out of 4) risk for severe thunderstorms across much of Southern Ontario on Wednesday, June 4th, 2025. They mention the potential for 90km/h damaging wind gusts, up to toonie size hail (2-3cm) and 50mm of rainfall that could bring isolated flooding. Timing looks to be from the afternoon to the evening for the strongest storms. Additionally, they mention a “minor” risk (1 out of 4) for thunderstorm activity on Thursday. We’ll break it down below.

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💨 Windy Wednesday

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Wednesday Morning:

The first storms are expected to arrive overnight Tuesday into Wednesday morning. These will mainly affecting portions of northeastern Ontario. This includes areas north of Sault Ste. Marie, stretching around Timmins and Moosonee towards the Quebec border and regions north of Lake Superior. Expect non-severe thunderstorms, with the main concern being isolated lightning strikes. While widespread heavy rain isn't the primary threat here, local rainfall amounts could reach up to 30 mm, with peak hourly rates around 15 mm. Environment Canada indicates a moderate confidence level for these initial storms.

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Wednesday Afternoon and Evening:

The afternoon and evening will bring a risk for severe thunderstorms across much of Southern Ontario. This area could experience isolated storms capable of producing a combination of strong winds, large hail, and heavy rain. Impacts could include damage to plants and crops, and loose objects could be tossed around by the gusty winds. There's also a risk of damage to weaker structures, broken tree branches and even downed trees. With the heavy rain, possible flash flooding and water pooling on roads are also concerns. Rainfall in these stronger storms could locally total up to 50mm, with intense peak hourly rates reaching up to 30mm. It's important to note that areas experiencing several rounds of thunderstorms have the strongest chance of seeing isolated flooding.

Interestingly, Environment Canada adds a caveat for these Southern Ontario storms: while some thunderstorms may indeed produce very gusty winds, hail, and torrential downpours, there's a possibility that smoke aloft might hinder their overall strength. This makes Environment Canada’s confidence of how severe these storms will become lower than normal for this type of setup, despite the potential for “moderate” to “high” impacts.

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⛈️ Thunder Thursday

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Thursday:

The likelihood of thunderstorms continues into Thursday across many parts of northern, far northern, and southern Ontario including areas like Windsor, London, Toronto, Hamilton, etc. Non-severe thunderstorms remain possible. Once again, isolated lightning strikes will be the main concern with local rainfall generally expected to be less than 15 mm. Environment Canada has moderate confidence in these storms developing.

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The focus Thursday shifts towards Eastern Ontario, highlighted as 'Area A' on the forecast map above. This area includes Ottawa, Cornwall, Perth, Brockville and areas east of Kingston. Stronger thunderstorms are possible, bringing hazards of strong winds and hail. If these storms strengthen as expected, they could damage plants and crops and toss loose objects. Environment Canada suggests these storms could produce wind gusts from 70-90 km/h and hail up to 2 cm (nickel size). Additionally, local rainfall amounts are expected to be up to 15 mm.

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🔎 Staying Safe and Prepared

As we move into summer and a more active weather pattern, it’s critical to stay informed! To keep a close eye on our latest forecasts and get notified of any alerts, download our free app Instant Weather, available on Apple and Android devices.

Remember the golden rule of lightning safety: "When thunder roars, go indoors!" as there is no safe place outside during a thunderstorm. Ahead of the storms, particularly on Wednesday afternoon and evening in Southern Ontario and throughout Thursday in Eastern Ontario, take a moment to secure any loose outdoor items before the storms arrive. Things like patio furniture, trampolines, and garbage cans can become projectiles in strong winds.

If you're planning to be on the roads, be prepared for challenging driving conditions such as sudden downpours, significantly reduced visibility, and the possibility of water pooling on roadways, especially in areas expecting heavier rainfall.

Stay safe everyone and if it’s safe to do so, share your reports with half a million community members on our Facebook group called Ontario Storm Reports!

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Disclaimer: These forecasts are issued by Environment Canada and typically published via their Twitter/X accounts. We receive these forecast via a daily email and often publish them to help inform our communities.

🌪️ ‘Tornado Tuesday’: Confidence Continues to Build For Significant Severe Thunderstorms Next Week in Ontario ⛈️

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TUESDAY, APRIL 29, 2025: Confidence continues to build for the risk of significant severe thunderstorms and tornado activity this Tuesday. Since our first article posted on Friday morning where we discussed this potential, we’ve continued to carefully monitor a strengthening trend on the forecast models. And at this point, we’re trending up from what initially looked like an Enhanced Risk (3/5), towards an isolated Significant Risk (4/5) based on the latest data. What we’re expecting at this point is isolated strong-to-significant severe thunderstorms across parts of Southwestern and Central Ontario Tuesday afternoon & evening that could possibly extend into the GTHA and parts of Eastern Ontario overnight, depending on the timing and speed of the cold front.

A lot can still change four days out but the consistency of the model data is why we here at InstantWeather have been discussing this for several days and why even Environment Canada has issued a preliminary forecast map today, discussing some of the risks on Tuesday including 100km/h damaging wind gusts and 2-4cm hail as you can see in the image below.

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Environment Canada, in their first forecast map for this event has not mentioned a tornado risk. This is likely because we’re four days out but based on the data that we’ll be reviewing below, we’d be very surprised if they did not add a tornado risk in their forecast update tomorrow. Along with this forecast map, they wrote:

”A cold front will track east across northeastern and southern Ontario. By the afternoon, severe thunderstorms may develop with the main threats being strong wind gusts and large hail.”

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🔎Model Data Review

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In the image above, we’re looking at the latest “NAM” model data for 5pm on Tuesday and what we’re reviewing is the “Supercell Index”. This gives us an idea of how potent the environment is for rotating storms, which can lead to damaging wind gusts, large hail, flooding, intense lightning and in some cases, tornadoes. In our previous article, we only saw an orange supercell risk which is roughly an “Enhanced” risk level (3/5). However, in the latest data we are now seeing the colour red, which is hinting at the potential for a “Significant” risk level (4/5).

And in the image below, we see what the “Supercell Index” looks like at 8pm from the same “NAM” model, continuing the strong environment into the evening hours and extending it further into Eastern Ontario.

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It’s still quite early but we’re now finally getting some higher quality data from the NAM model at 12km resolution and what you’re seeing above is simulated or “Future Radar” of how the event might play out. It’s still quite early and this could certainly change but it’s interesting to watch it evolve day-by-day. With this model run, the storms start to develop on the Lake Huron shoreline near the Kincardine and Goderich areas around 5pm. We do see some development up by Britt as well around that time. Again, this is just estimated and we could see a new solution to how this plays out each and every day leading up to Tuesday.

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By 8pm in the image above, the simulated NAM future radar is suggesting we could see several potent supercells tracking through parts of Southwestern and Central Ontario. In previous model runs, we have seen a large line of storms as well, which in some cases can limit the tornado risk. Although, we could end up dealing with multi-cell supercells with an environment this strong and those can most certainly produce strong, isolated tornadoes.

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And in this potential scenario from the NAM model, we still the storms expanding and tracking through deep Southwestern Ontario, Central Ontario and perhaps into parts of Eastern Ontario by 11pm. Typically, the later in the evening we get, the less we daytime heating we have to increase the severity of these storms but with how strong this environment is, it could be a late night for many of us and we’ll certainly be livestreaming as long as it takes to ensure everyone stays informed and safe.

If you’d like to get notified when we start livestreaming, subscribe to our YouTube channel for free and hit the bell icon to get notified when we go live.

And to get notified of any rotation detected, funnel cloud reports, tornado reports and Environment Canada watches & warnings, download our free mobile app InstantWeather on your phone or tablet.

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🤔Final Thoughts:

If this trend continues and this system does not decide to weaken all of the sudden (here’s hoping it does), Tuesday continues to look like a strong or potentially significant severe thunderstorm risk. All modes of severe weather could be on the table with damaging wind gusts, torrential rain, isolated flooding, large hail, intense lightning and the potential for isolated tornadoes, some of which could be strong. Here’s hoping that it weakens into a marginal risk or vanishes all together!

Having said that, please begin to review your storm safety plan and start discussing the potential for rescheduling your Tuesday afternoon/evening plans.

More details ASAP.

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Disclaimer: By using our services and any associated content, this means you implicitly agree to use the services and data available as is with no warranty issued or implied and should be used for informational purposes only. Any use of this data for decision making processes is done at the sole risk of the end user. Do not reproduce or disseminate our forecasts and content without explicit consent of Instant Weather, Inc.

🌪️ ‘Tornado Tuesday’ Might Make a Return in Southern Ontario Next Week ⛈️

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TUESDAY, APRIL 29, 2025: As I write this discussion (2am on Friday, April 25th, 2025), we’re quite a few days away from Tuesday, April 29th, 2025. Having said that, I’ve been carefully monitoring this strengthening trend on the forecast models for several days now and seeing them consistently suggesting an enhanced risk (3/5) for severe thunderstorms across much of Southern Ontario with the potential for isolated tornado activity. From Windsor, up through Barrie and perhaps even reaching parts of Eastern Ontario and the GTHA.

Typically, five days out is a lifetime for forecasting severe weather. Having said that, in rare circumstances you can see these strong environments coming from a mile away and this looks like this could be one of those events. Especially when we have a lot of data supporting the risk, which we’ll discuss further down the page.

Could this all change? You betcha. After more than a decade of forecasting severe weather in Ontario and across Canada, I’m no stranger to the potential for a “bust”. I could write this article and the entire system could vanish from the weather models. Tuesday could end up being just another typical spring day. Here’s hoping that’s the case. If, however, that is not the case and the trends we’re seeing in the models are correct, this is the type of event that requires getting the word out well in advance so that alternative plans can be considered and you can review your safety plan with your loved ones.

FRIDAY, APRIL 25, 2025: I should probably mention that we will have a risk for isolated thunderstorms today (Friday) and there is a marginal (low) risk for severe storms in deep southwestern Ontario later this afternoon and into the evening hours. Briefly severe hail and strong wind gusts are possible. At this point, it doesn’t look particularly intense but we’ll be keeping a close eye on it, nonetheless.

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🔎Reviewing Models & Available Data For Tuesday

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Typically, we like to compare the data from several different model systems. In this case, we’ll compare the American model, the European model and our own Canadian model. In the image above, we’re looking at the American model and what we’re reviewing is the severe weather “energy” that the storms are going to have available to them. The highest levels reaching almost 2,500 (in yellow/orange), which puts this event in the ‘Enhanced 3/5’ category, in my personal opinion.

For context, we can have marginal severe weather with energy levels as low as 500. And on the high-end, CAPE can reach as high as 5,000+ in the most extreme cases. So we’re somewhere in the middle, with totals potentially reaching greater than 1,000 and less than 3,000, at least, at this point.

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Above is the Euro model, showing similar strong values to the American model in the deep southwest at 2pm. But, as you’ll see below, the energy progresses further east as we approach 5pm on Tuesday.

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Above, we’ve got the 5pm timeframe from the Euro model. Showing organized energy values in place for the expected thunderstorms in the afternoon and evening hours.

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While we’re taking a look at the European model, one interesting product they have is an estimated lightning density over several hours. As you can see in red, orange yellow and blue, quite a lot of thunderstorms are expected throughout the afternoon and into the evening hours, taking advantage of all that storm energy we discussed previously.

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Below, let’s take a look at the Canadian energy for Tuesday. For some reason, the data looks really blocky. Not sure why PivotalWeather.com (the model provider we’re using for these images) is processing the Canadian model this way but perhaps, it’s coming that way directly from Environment Canada.

Regardless, a similar trend is showing up on the Canadian model that we’re seeing on both the European and American models. And with that, we have what is considered “model agreement”. And it’s not just these three models, other forecasting products called ‘Ensembles’ have 30+ model members and the vast majority are showing a strong severe thunderstorm risk for Tuesday.

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This Canadian model image above is for 2pm on Tuesday. And similar to the European model data where we showed two separate timestamps (2pm and 5pm), this energy will push east, through the Barrie area and potentially into the GTHA and parts of Eastern Ontario through the afternoon and evening hours. Energy values look similar to the other two models, supporting the potential for an Enhanced Risk of severe thunderstorms.

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Some other data worth noting in the image below is from the Storm Prediction Center (SPC) in Norman, Oklahoma. Not surprisingly, they are already showing a risk map for Tuesday, which they typically only show this far out when there is a strong system expected and a lot of agreement within the weather models.

You can see that southwestern Ontario gets highlighted in this risk area from Windsor, through Chatham-Kent and Sarnia, cutting off just shy of London. Having said that, the SPC’s only job is to forecast for the US. And as we’ve seen historically with them over the past decade, if they’re showing an extended range forecast that highlights parts of Southern Ontario, we could be in for quite the storm system much further into the Province than is shown below.

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And in the final image below, we’re looking at a Machine Learning (AI) based severe weather estimation from the US. In this case, they cut off the data at the international border but by simply using your imagination, it’s clear that Southern Ontario is included in this risk region.

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🤔Final Thoughts:

If these trends continue and this system does not decide to vanish from all the models suddenly (here’s hoping it does), Tuesday is shaping up to be a strong or potentially significant severe thunderstorm risk. All modes of severe weather could be on the table with damaging wind gusts, torrential rain, isolated flooding, large hail, intense lightning and the potential for isolated tornadoes, some of which could be strong. Here’s hoping that it weakens into a marginal risk or vanishes all together!

Having said that, now would be a good time to start reviewing your storm safety plan and discussing your plans for Tuesday if this system does decide to show up and affect Southern Ontario.

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Disclaimer: By using our services and any associated content, this means you implicitly agree to use the services and data available as is with no warranty issued or implied and should be used for informational purposes only. Any use of this data for decision making processes is done at the sole risk of the end user. Do not reproduce or disseminate our forecasts and content without explicit consent of Instant Weather, Inc.

Post-Easter Storm Could Bring Up to 20cm of Snow to Parts of Saskatchewan and Manitoba

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As we get later into the month of April, there have already been tastes of warm weather across the Prairies, with temperatures climbing into the upper teens and low 20s across parts of all three provinces. Don’t let that fool you because it is still spring in the region and that means the continued possibility of heavy snowfall events. This will be the case beginning Tuesday morning and continuing into Wednesday for parts of Saskatchewan and Manitoba.

Model Image showing the location and intensity of snow (Blue) and Rain (Green) at 5AM cT Tuesday

Steady light snow is expected to continue in West Central Saskatchewan overnight Monday and into Tuesday morning. Early Tuesday morning, a low pressure system will push northward from North Dakota, bringing precipitation to Southeastern Saskatchewan and Southern Manitoba. The two areas of snow will merge before sunrise, creating a wide band of continuous snowfall.

As the morning progresses, the system will stall and the light snow in Western Saskatchewan will taper off. On the other hand, the snowfall will intensify along the Saskatchewan-Manitoba border. Further eastward, into the Central Plains and across to the Ontario border, above-freezing temperatures will result in the precipitation from this system falling as rain.

Model Image showing the location and intensity of snow (Blue) and Rain (Green) at 7pM cT Tuesday

Most of the snow will clear in Saskatchewan through Tuesday afternoon, leaving only the area of heavier snow on both sides of the Manitoba border by the evening. The snowfall will persist over this area overnight and it will gradually dissipate throughout the early morning hours.

In this area of constant snowfall, which includes Melville, Moosomin, and Yorkton in Saskatchewan, as well as Dauphin, Roblin, and Russell in Manitoba, residents can expect up to 20cm of snow accumulation by mid Wednesday morning. Depending on how much intensification we see Tuesday morning, it’s possible that up to 25cm could fall locally.

This much snow over a brief period will definitely make travel tricky throughout the day Tuesday so make sure to take extra caution when out on the roads.

The Never-Ending Winter Continues for Southern Ontario; Snowy System Could Dump Up to 25cm by Tuesday

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Residents across Southern Ontario, especially in the snowbelt regions, have certainly had their fair share of winter weather this season. From intense snow squalls back in December to the crippling ice storm that hit parts of Central Ontario just last month, it's no wonder that many are ready to say goodbye to winter.

Unfortunately, it seems that Mother Nature didn’t get the memo. Spring-like weather remains out of sight for at least the next week. Instead, the region is facing below-seasonal temperatures, with many areas struggling to reach the freezing mark during the day. On top of that, a fast-moving weather disturbance is currently affecting Northeastern Ontario with heavy snow. This system is expected to push into Southern Ontario late Monday as a cold front makes its way through the region.

Snowfall will intensify overnight and continue into Tuesday morning. The heaviest bands are expected across northern portions of Central Ontario and through the Ottawa Valley. Snowfall totals in these areas could easily exceed 15 cm, with some locations possibly seeing as much as 25 cm.

Elsewhere in Southern Ontario, lake enhancement and lake effect snow behind the system could lead to locally higher amounts—anywhere from 5 to 15 cm is possible around Lake Huron and along the southern shores of Georgian Bay.

Strong wind gusts of up to 80 km/h are also expected Monday evening into the early overnight hours around Georgian Bay, Lake Huron, and parts of Central Ontario. These gusts may create blowing snow and significantly reduce visibility at times.

More concerning, though, is the impact these winds could have on restoration efforts in areas still reeling from last month’s devastating ice storm. With nearly 50,000 Hydro One customers still without power after 10 days, additional outages are possible as the already fragile infrastructure struggles under the pressure of these gusty conditions.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

As of Monday evening, heavy snow continues to fall across the Sudbury and North Bay regions, both of which have seen a significant dumping of snow throughout the day. By the time conditions begin to improve later this evening, localized snowfall totals will likely surpass 20 cm.

Further south, a sharp cold front is pushing a line of heavy snow across Southern Ontario over the next few hours. Along with the sudden drop in temperatures, this front could bring a quick burst of intense snowfall, leading to brief whiteout conditions and rapid accumulation.

Temperatures are still hovering just above freezing ahead of the front, which should help limit how much of the snow sticks at first, as the wet snow may melt upon contact with the relatively warm ground.

ESTIMATED WIND GUSTS- MAP FROM WEATHERBELL

Another concern this evening will be the development of strong wind gusts near Lake Simcoe and extending into parts of the Golden Horseshoe. Wind speeds could reach 60 to 80 km/h in localized areas.

While those wind speeds wouldn’t normally cause widespread issues, the combination of gusty winds and heavy snow could lead to pockets of blowing snow and reduced visibility, especially on the roads.

This area is also still recovering from the recent ice storm, with ongoing power restoration efforts in regions like Simcoe County, Peterborough, and the Kawartha Lakes. The added strain from tonight’s strong winds could cause further damage to the already weakened power grid in those communities.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

After midnight, the focus of the heaviest snow will shift eastward into the Ottawa Valley. Persistent, moderate to heavy snow is expected across the region, especially in and around the City of Ottawa. One key area we’ll be closely monitoring is just west of Ottawa, where forecast models are showing the potential for a pocket of very heavy snowfall.

Communities including Algonquin Park, Barry’s Bay, Pembroke, and Petawawa could be directly impacted by this locally intense band of snow. If it shifts slightly east, it may sneak into Ottawa itself—something that could have a major effect on the Tuesday morning commute. Snowfall rates in this band may exceed 5 cm per hour, leading to near-whiteout conditions.

Additionally, more localized lake-effect snow bands could develop off Lake Huron and Georgian Bay early Tuesday. Based on current guidance, one of these bands may impact parts of Huron and Perth counties, with a small chance of reaching the London area, though whether or not London sees any snow will depend on exactly where the band sets up. Some weaker snow activity is also expected near the southern shores of Georgian Bay, including places like Owen Sound, Meaford, and Collingwood.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By Tuesday morning, snowfall will begin to taper off from west to east across the region. The Ottawa Valley will continue to see steady snow past sunrise, although it should begin to lighten up by early afternoon.

Lingering lake effect snow flurries may continue near Lake Huron and Georgian Bay, but are also expected to wind down by late morning as the system finally pulls away.

ESTIMATED WIND CHILL - MAP FROM WEATHERBELL

In addition to the snow, Tuesday will bring a blast of bitterly cold Arctic air to much of Southern Ontario. This late-season cold snap will make it feel especially harsh for those heading out in the morning. Once the wind chill is factored in, it could feel like the -20s across parts of Central Ontario.

Make sure to dress warmly, especially if you've already switched to a spring wardrobe. It might be time to dig out that heavy winter coat once again.

The frigid temperatures also pose an added risk for anyone still without power following the ice storm. Be sure to check in on friends, family, and neighbours who may be vulnerable to the cold, and if needed, make use of warming centres set up in the hardest-hit communities.

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The highest snowfall totals from this system are expected in the northern sections of Central and Eastern Ontario, including places like Sudbury, North Bay, northern Muskoka, Algonquin Park, Pembroke, Renfrew, and Ottawa. These areas are likely to receive 15 to 25 cm of snow in total, including the accumulation that began earlier on Monday.

Elsewhere in Central Ontario and extreme Eastern Ontario, along with areas east of Lake Huron, snowfall totals are expected to fall in the 5 to 15 cm range. The wide range is due to uncertainty about how much snow will stick, as the heaviest snowfall is forecast while temperatures hover near or just above freezing. Affected areas include Grand Bend, Goderich, Kincardine, Grey-Bruce, Collingwood, Simcoe County, Muskoka, Bancroft, Brockville, and Cornwall.

For much of Southern Ontario, less than 5 cm is expected, with the Golden Horseshoe likely seeing no more than a dusting. In Deep Southwestern Ontario, including Windsor, Chatham, and Sarnia, little to no accumulation is expected from this system.

⚠️ Flood Warnings Issued for Kitchener, Cambridge and More Ontario Communities on Thursday ☔️

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Heavy rainfall and rapid snowmelt are triggering rising water levels across much of Southern Ontario, prompting multiple flood warnings and watches being issued since this past Friday. Conservation authorities and the Ministry of Natural Resources (MNR) have issued alerts for various watersheds, warning that saturated ground conditions and increased runoff may lead to localized flooding. Residents in affected areas should remain vigilant as rivers and streams swell, with the risk of minor to moderate flooding in low-lying regions.

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New Flood Warnings

The Grand River Conservation Authority (GRCA) is issuing a Flood Warning message for the City of Kitchener and the City of Cambridge. The Flood Warning message previously issued for West Montrose is being upgraded to Flood Warning Zone 2. The Flood Warning messages previously issued for Grand Valley, Waldemar, Drayton, the Village of Conestogo, New Hamburg, and Ayr remain in effect.

Weather forecast

Temperatures in the watershed have increased to double digits above freezing overnight and are expected to remain high for the remainder of the day. A mixed precipitation event, including snow, freezing rain, and rain, began yesterday and continued overnight throughout the watershed. This has resulted in approximately 40 to 80 mm of total precipitation and increased runoff throughout the watershed.

Flood Warning Message for the City of Kitchener

The Grand River is expected to overflow its banks midday Thursday, April 3, increasing the risk of flooding in low-lying areas. Municipal flood coordinators in the City of Kitchener have been advised to notify affected properties and monitor conditions.

Flood Warning Message for the City of Cambridge

The Grand River is expected to overflow its banks near Water Street/Highway 24 on midday Thursday, April 3. Municipal flood coordinators in the City of Cambridge have been advised to notify affected properties and monitor conditions.

Flood Warning Message for West Montrose

River flows are expected to reach Flood Warning Zone 2 in West Montrose the afternoon of Thursday, April 3. Municipal flood coordinators in the Township of Woolwich have been advised to notify affected properties and monitor conditions. Residents are encouraged to refer to the guide on the GRCA’s website for information regarding flood warning zones.

Flood Warning Message for Grand Valley and Waldemar

River flows are expected to exceed channel capacity and peak midday Thursday, April 3. Municipal flood coordinators in Grand Valley and Waldemar have been advised to notify affected properties and monitor conditions.

Flood Warning Message for Drayton

River flows are expected to reach Flood Warning Zone 1 in Drayton on Thursday, April 3, during the morning. Municipal flood coordinators in the Township of Mapleton have been advised to notify affected properties and monitor conditions. Residents are encouraged to refer to the guide on the GRCA’s website for information regarding flood warning zones.

Flood Warning Message for the Village of Conestogo

River flows are expected to reach flooding thresholds in the Village of Conestogo midday Thursday, April 3. Municipal flood coordinators in the Township of Woolwich have been advised to notify affected properties and monitor conditions.

Flood Warning Message for New Hamburg

River flows are expected to reach Flood Warning Zone 2 in New Hamburg midday Thursday, April 3. Municipal flood coordinators in the Township of Wilmot have been advised to notify affected properties and monitor conditions. Residents are encouraged to refer to the guide on the GRCA’s website for information regarding flood warning zones.

Flood Warning Message for Ayr

River flows are expected to reach Flood Warning Zone 2 in Ayr on the morning of Friday, April 4. Municipal flood coordinators in the Township of North Dumfries have been advised to notify affected properties and monitor conditions. Residents are encouraged to refer to the guide on the GRCA’s website for information regarding flood warning zones.

This message will remain in effect until 12 p.m. on Saturday, April 5, 2025. 

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Flood Warnings

MNR Districts:

- Aurora, Midhurst, Owen Sound – *Flood Warning* (April 2, 2025, 12:30 PM)

- Minden, Parry Sound, Bracebridge – *Flood Warning* (March 28, 2025, 2:30 PM)

- Peterborough, Bancroft (Burnt and Black Rivers) – *Flood Warning* (March 28, 2025, 12:00 AM)

Conservation Authorities:

- Grand River – *Flood Warning* (April 3, 2025, 8:30 AM) NEW

- Nottawasaga Valley – *Flood Warning* (April 1, 2025, 1:30 PM)

- Otonabee Region – *Flood Warning* (April 2, 2025, 1:00 PM)

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Flood Watches

MNR Districts:

- Peterborough, Bancroft – *Flood Watch* (March 27, 2025, 10:00 AM)

Conservation Authorities:

- Ausable Bayfield – *Flood Watch* (April 1, 2025, 3:00 PM)

- Cataraqui Region – *Flood Watch* (April 1, 2025, 11:30 AM)

- Crowe Valley – *Flood Watch* (April 2, 2025, 2:00 PM)

- Essex Region – *Flood Watch* (April 1, 2025, 4:30 PM)

- Grey Sauble – *Flood Watch* (April 1, 2025, 11:00 AM)

- Hamilton Region – *Flood Watch* (March 31, 2025, 10:30 AM)

- Hamilton Region (High Great Lakes Level) – *Flood Watch* (April 1, 2025, 3:30 PM)

- Kawartha Region – *Flood Watch* (March 31, 2025, 12:00 AM)

- Kettle Creek – *Flood Watch* (April 2, 2025, 4:00 PM)

- Lower Trent – *Flood Watch* (April 2, 2025, 4:30 PM)

- Maitland Valley – *Flood Watch* (April 2, 2025, 10:30 AM)

- Mississippi Valley – *Flood Watch* (April 2, 2025, 4:00 PM)

- Niagara Peninsula – *Flood Watch* (April 2, 2025, 10:00 AM)

- Rideau Valley – *Flood Watch* (March 27, 2025, 4:15 PM)

- Saugeen Valley – *Flood Watch* (April 1, 2025, 12:00 AM)

- South Nation River – *Flood Watch* (March 28, 2025, 1:30 PM)

- St. Clair Region – *Flood Watch* (April 2, 2025, 11:00 PM)

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Watershed and Shoreline Conditions Statements

Water Safety Statements:

- Catfish Creek – *Watershed Conditions Statement – Water Safety* (April 2, 2025, 8:30 AM)

- Ganaraska Region – *Watershed Conditions Statement – Water Safety* (April 1, 2025, 3:30 PM)

- North Bay – *Watershed Conditions Statement – Water Safety* (March 28, 2025, 3:00 PM)

- Pembroke – *Watershed Conditions Statement – Water Safety* (March 28, 2025, 12:00 PM)

- North Bay-Mattawa – *Watershed Conditions Statement – Water Safety* (March 28, 2025, 2:30 PM)

- Raisin Region – *Watershed Conditions Statement – Water Safety* (March 24, 2025, 10:00 AM)

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Flood Outlook Statements

- Central Lake Ontario – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 12:00 AM)

- Credit Valley – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 11:30 AM)

- Halton Region – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 12:00 AM)

- Lake Simcoe Region – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 4:00 PM)

- Long Point Region – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 3:30 PM)

- Lower Thames Valley – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 2:00 PM)

- Quinte (Inland Lakes and Rivers) – *Watershed Conditions Statement – Flood Outlook* (March 27, 2025, 12:00 PM)

- Toronto and Region – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 1:30 PM)

- Upper Thames River – *Watershed Conditions Statement – Flood Outlook* (April 1, 2025, 2:30 PM)

- **Shoreline Conditions Statement – Storm Surge:**

- Catfish Creek – *Shoreline Conditions Statement – Storm Surge* (December 11, 2024, 12:00 AM)

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Flood Risks and Safety Tips

With continued snowmelt and upcoming rainfall, many rivers and streams remain at risk of rising beyond their banks, especially in central and eastern Ontario. The combination of warm temperatures and precipitation is accelerating runoff, leading to swollen waterways with reduced capacity to handle additional rainfall. Minor flooding in low-lying areas is expected, with localized road closures possible.

- Stay informed by monitoring local weather forecasts, special weather statements, and emergency alerts.

- Avoid low-lying areas prone to flooding and never attempt to drive through flooded roads.

- Secure outdoor belongings that could be carried away by rising waters.

- If you live in a flood-prone area, prepare an emergency kit with essentials in case of evacuation.

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Final Thoughts:

As flood warnings and watches continue across parts of Southern Ontario, it's important for residents in affected areas to stay alert and prepared. The combination of rapid snowmelt, saturated ground conditions, and forecasted rainfall means that water levels could rise quickly, increasing the risk of localized flooding. Keep an eye on weather updates, follow official advisories, and take precautions to protect your home and safety. If you live in a flood-prone area, now is the time to review your emergency plan. Stay safe, stay informed, and let’s hope for drier days ahead!

⛈️Severe Thunderstorm Risk, More Freezing Rain, Heavy Rain, Snow, and Strong Wind Gusts on Wednesday in Ontario

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Spring storms are here, and this one is bringing a bit of everything. It will begin Wednesday morning delivering heavy rain, freezing rain, strong wind gusts, severe thunderstorms and snow depending on your location. Southwestern Ontario will see significant rainfall and a severe thunderstorm risk, while parts of central, eastern, the golden horseshoe and northeastern Ontario could face a messy mix of freezing rain, ice pellets, rain, snow and strong wind gusts, again, depending on your location. For those still recovering from last weekend’s ice storm, this storm could certainly add to the challenges. There’s also a risk for substantial snowfall in northwestern Ontario, specially in the Thunder Bay region. Further details on each area below.

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⛈️Severe Thunderstorm Risk

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💨🌪️ Hazard(s): Wind, Tornado, Thunderstorms
📍 Location: Extreme southwestern Ontario
⏳ Timing: Late Wednesday afternoon and evening.
⚠️ Impact(s): Loose objects may be tossed, possible power outages

🔎 Confidence: Low
💥 Impact: High

A line of severe thunderstorms could cross into the province from Michigan, possibly producing wind gusts up to 100 km/h. A brief tornado is also possible on this line. There is lots of uncertainty in this occurring as ingredients to form these thunderstorms are located well south of the border and will rely on the thunderstorms being able to develop there and reach southwestern Ontario before weakening. Refer to the Wednesday Significant Weather discussion for rainfall information.

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🌧️ Heavy Rain, 🧊 Ice, 💨 Strong Wind Gusts, and ❄️ Snow

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📍 Location: Southwestern Ontario

🌧️ Hazard(s): Rain
📍 Location: Southwestern Ontario
⏳ Timing: Wednesday morning into Thursday morning
⚠️ Impact(s): Possible flooding in low-lying areas

🔎 Confidence: Moderate
💥 Impact: High

Rain is expected and may be accompanied by thunderstorms. Rainfall amounts up to 60 mm are possible by late Wednesday evening, with additional amounts expected on Thursday. Totals will vary, with areas east of Lake Huron receiving up to 60 mm, while regions near Lake Erie will likely see 10 to 20 mm.

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📍 Location: Grey and Bruce Counties east to Peterborough

🧊🌧️ Hazard(s): Ice, Rain
📍 Location: Grey and Bruce Counties east to Peterborough
⏳ Timing: Wednesday midday into Thursday morning
⚠️ Impact(s): Possible flooding in low-lying areas, broken tree branches from ice build-up

🔎 Confidence: High
💥 Impact: High

Freezing rain, possibly mixed with ice pellets, is expected to bring 4 to 8 mm of ice accretion on some surfaces, particularly over higher terrain. Rain will follow and may be accompanied by thunderstorms. Rainfall amounts up to 40 mm are possible by late Wednesday evening, with more rain on Thursday.

⚠️ Impacts in this area may be enhanced due to recovery efforts from last weekend’s ice storm.

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📍 Location: East of Lake Huron to portions of the Greater Golden Horseshoe

🌧️🧊 Hazard(s): Rain, Ice
📍 Location: East of Lake Huron to portions of the Greater Golden Horseshoe
⏳ Timing: Wednesday midday into Thursday morning
⚠️ Impact(s): Possible flooding in low-lying areas, possible icy surfaces on roads and walkways.

🔎 Confidence: Moderate
💥 Impact: High

A brief period of freezing rain is expected Wednesday afternoon, bringing 1 to 2 mm of ice accretion on some surfaces, particularly over higher terrain. Rain will follow and may be accompanied by thunderstorms. Rainfall amounts up to 50 mm are possible by late Wednesday evening, with more rain on Thursday.

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📍 Location: Parts of Central, Eastern and Northeastern Ontario

❄️🧊 Hazard(s): Snow, Ice
📍 Location: East of Lake Huron to portions of the Greater Golden Horseshoe
⏳ Timing: Wednesday midday into Thursday morning
⚠️ Impact(s): Broken tree branches from ice build-up, possible difficult travel conditions

🔎 Confidence: Moderate
💥 Impact: High

A messy mix of winter precipitation is expected. Snow mixed with ice pellets will develop near midday Wednesday, with up to 5 cm possible before transitioning to freezing rain. A period of freezing rain Wednesday evening could bring 3 to 6 mm of ice accretion, especially over higher terrain.

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📍 Location: North shore of Lake Ontario

🧊🌧️ Hazard(s): Ice, Rain
📍 Location: North shore of Lake Ontario
⏳ Timing: Wednesday midday into Thursday
⚠️ Impact(s): Possible icy surfaces on roads and walkways, possible flash flooding and water pooling on roads

🔎 Confidence: Moderate
💥 Impact: Low

A brief period of ice pellets or freezing rain is possible Wednesday afternoon. Rain will follow and may be accompanied by thunderstorms. Rainfall amounts up to 20 mm are possible by late Wednesday evening, with additional amounts expected on Thursday.

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📍 Location: Southern portions of Northeastern Ontario and portions of Eastern Ontario

❄️🧊 Hazard(s): Snow, Ice
📍 Location: Southern portions of northeastern Ontario and portions of eastern Ontario
⏳ Timing: Beginning midday Wednesday
⚠️ Impact(s): Difficult travel conditions

🔎 Confidence:
💥 Impact:

A messy mix of winter precipitation is expected. Snow mixed with ice pellets will develop Wednesday afternoon, with up to 5 cm possible before transitioning to a brief period of freezing rain.

⚠️ Confidence in ice accretion amounts is low. However, accretion is expected to remain fairly low as the freezing rain transitions to rain Wednesday night.

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📍 Location: West of Lake Superior

❄️🌬️ Hazard(s): Snow, Blowing Snow
📍 Location: West of Lake Superior
⏳ Timing: Wednesday morning into Thursday morning
⚠️ Impact(s): Difficult travel conditions, reduced visibility, possible road closures

🔎 Confidence:
💥 Impact:

Snowfall amounts up to 25 cm are possible, with locally higher totals over elevated terrain. Gusty winds could lead to local blowing snow, especially near Lake Superior. Additional snowfall is expected Thursday.

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📍 Location: Northwestern Ontario and north of Lake Superior

❄️ Hazard(s): Snow
📍 Location: Northwestern Ontario and north of Lake Superior
⏳ Timing: Wednesday morning into Thursday morning
⚠️ Impact(s): Difficult travel conditions

🔎 Confidence:
💥 Impact:

Snowfall amounts up to 15 cm are possible, with additional snowfall expected Thursday.

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Final Thoughts:

This is shaping up to be a potentially strong system with widespread rain, ice, and snow affecting much of Ontario. Flooding, icy roads, tree damage, and power outages are all possible. For areas still recovering from last weekend’s ice storm, even small amounts of ice could exacerbate existing damage. The severe thunderstorm risk in deep southwestern Ontario is of particular concern as well.

As always, keep an eye our latest updates and prepare for rapidly changing conditions. Stay safe out there, folks!

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Disclaimer: These forecasts are issued by Environment Canada and typically published via their Twitter/X accounts. We receive these forecast via a daily email and often publish them to help inform our communities.

Dangerous Ice Storm Likely This Weekend With Widespread Power Outages Across Parts of Southern Ontario

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Concern is rapidly growing for what is shaping up to be a potentially devastating ice storm this weekend across parts of Central and Eastern Ontario. Prolonged freezing rain, beginning Friday evening, is expected to persist throughout much of the weekend, leading to substantial ice accretion on exposed surfaces.

This storm has the potential to reach ice accumulation levels not seen in years—or even over a decade. With up to 40mm of ice accretion possible, widespread power outages are likely in the hardest-hit regions, including Muskoka, Simcoe County, Kawartha Lakes, Peterborough, and Kingston.

Some of these power outages could last for days or even weeks, especially in more rural areas with dense tree coverage. Trees weighed down by ice are likely to fall, taking power lines with them. Travel conditions will also be significantly impacted, as ice-covered roads become extremely dangerous.

For Northern Ontario, the storm will start as a classic winter system, bringing heavy snowfall to Northeastern Ontario throughout Saturday. A second round of precipitation on Sunday could introduce freezing rain and ice pellets further south, affecting areas like Elliot Lake, Sudbury, and North Bay. Snowfall totals in Northeastern Ontario are expected to range from 20 to 30cm, making travel difficult.

Even the Ottawa Valley will see significant snowfall, with up to 20cm possible, along with a mix of ice pellets. By Sunday, freezing rain could become a concern for the region as temperatures rise and the precipitation type shifts.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

As of Friday afternoon, rain is already moving into Southwestern Ontario. By the evening, precipitation will spread north and east into Central and Eastern Ontario.

Based on the latest data, a band of heavy snow is expected to develop along a corridor stretching from Sudbury through North Bay and into the Ottawa region. To the south, an area of freezing rain will form over the Bruce Peninsula and extend into regions around Lake Simcoe.

ESTIMATED TEMPERATURE - MAP FROM WEATHERBELL

How far south the freezing rain spreads remains uncertain. Model guidance suggests surface temperatures will hover near the freezing mark across Barrie and the Greater Toronto Area (GTA).

Even a fraction of a degree difference could significantly alter how much freezing rain accumulates. If the air remains colder than expected, freezing rain could be more widespread. However, a slightly warmer scenario would push the freezing rain line further north.

Confidence is highest for freezing rain in northern sections of Simcoe County, Kawartha Lakes, and Muskoka. These areas are most likely to remain below freezing for an extended period, allowing heavy ice accretion to build up.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The most intense icing is expected overnight into early Saturday morning. The worst conditions will stretch from Muskoka through Peterborough and into Kingston.

Once again, temperature will be the deciding factor. Some areas, such as Barrie and Newmarket, sit right on the edge between freezing rain and regular rain. If cold air lingers longer than anticipated, freezing rain could extend as far south as the northern GTA, as well as higher elevations like the Dundalk Highlands.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Through Saturday morning and afternoon, light to moderate freezing rain or drizzle is expected to persist across portions of Central Ontario, particularly around Lake Simcoe. However, the intensity will decrease compared to the earlier hours.

Further south, rain will continue across Southwestern Ontario and the GTA. This is when we expect the warmest temperatures of the storm. Some areas in Deep Southwestern Ontario, including Windsor, could surge into the 20s, while Central Ontario remains near or below freezing.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

By Saturday evening, another round of heavy precipitation is expected to push into Central Ontario. At the same time, temperatures will steadily drop. Regions that saw rain in the afternoon—including parts of the GTA and Barrie—may transition back to freezing rain.

ESTIMATED TEMPERATURE - MAP FROM WEATHERBELL

Model data suggests that by late Saturday night into Sunday morning, the freezing rain line could shift southwest of the GTA. This could result in several hours of freezing rain across Kitchener, Waterloo, and parts of the Toronto area.

Deep Southwestern Ontario, including Windsor, Sarnia, and London, is expected to remain unaffected, staying well above freezing.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Sunday morning will bring a gradual transition from freezing rain to regular rain across the GTA as temperatures climb above freezing. However, elevated areas northwest of the city, such as Guelph, Orangeville, and Shelburne, could see freezing rain linger for a few extra hours.

For Central Ontario, the freezing rain will continue into early Sunday afternoon as the main area of precipitation slowly shifts north.

By Sunday afternoon, the Ottawa Valley may begin transitioning from snow to ice pellets and then to freezing rain as temperatures rise.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Most of Southern Ontario will warm above the freezing mark by late Sunday, finally pushing the freezing rain threat northward.

However, by Sunday night into Monday morning, the risk of freezing rain will shift to Northeastern Ontario, including Sudbury and North Bay.

Meanwhile, heavy snow and ice pellets will impact more northern regions, such as Wawa and Timmins.

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Predicting exact ice accretion remains challenging, as many factors influence how much ice actually builds up. The amount of freezing rain you experience may vary significantly from nearby areas due to microclimate effects, surface conditions, and temperature fluctuations.

Some high-resolution model runs suggest an extreme scenario with localized pockets of over 50mm—possibly even 75mm—of freezing rain. However, because much of this precipitation will fall in a relatively short timeframe, not all of it will necessarily adhere to surfaces.

Given this, we are forecasting general ice accretion between 25 and 40mm in the hardest-hit areas. This includes the northern tip of the Bruce Peninsula, Muskoka, Orillia, Barrie, Orangeville, Collingwood, Lindsay, Peterborough, Belleville, and Kingston.

If temperatures are slightly colder than expected, some locations could exceed 40mm of ice accretion, particularly where conditions allow for more efficient accumulation.

To put this into perspective, we can use the Sperry-Piltz Ice Accumulation Index (SPIA Index). With forecasted ice accumulations of 25-40mm (1-1.4”), this storm falls into a Category 4 ice event—even before factoring in wind.

While we are not expecting extreme winds, gusts of 40-50km/h (25-30 mph) in some areas could push this storm into Category 5 territory. According to the SPIA Index, a Category 5 ice storm results in:

Catastrophic damage to entire exposed utility systems, including both distribution and transmission networks. Outages could last several weeks in some areas. Shelters needed.

For the Greater Toronto Area (GTA), ice accretion amounts will vary significantly. The biggest factor will be how long cold air remains trapped at the surface.

We currently expect between 10-15mm of ice for northern parts of the GTA, including York, Durham, and Peel regions. Kitchener and Waterloo will likely see between 5-10mm.

Closer to the Lake Ontario shoreline—including downtown Toronto—freezing rain amounts should be lower, around 2-5mm. However, if temperatures are colder than expected, ice accretion in the GTA could be higher, so it’s still best to prepare.

To the north, ice accretion amounts will drop off as freezing rain transitions to ice pellets and snow closer to the Ottawa Valley.

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In terms of snowfall, widespread totals between 20-30cm are expected across much of Northeastern Ontario through Monday. This includes Sudbury, North Bay, Chapleau, Timmins, and Kirkland Lake. Even Thunder Bay could see 10-20cm of snow, mainly earlier in the weekend.

Along the Quebec border, snowfall amounts will range from 10-20cm in areas like the Ottawa Valley and Cornwall. Further southwest, freezing rain and ice pellets will be the dominant concern, leading to lower snowfall totals.

This storm remains highly dynamic, with small temperature fluctuations potentially making a massive difference in what type of precipitation falls. We will continue to monitor the latest data and provide updates as the situation evolves. Stay safe and stay prepared.

Significant Spring Storm Expected to Dump up to 20cm and Possibly Locally Higher Amounts Across the Prairies

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It’s simply not spring in the Prairies without at least one major snowstorm and this year will be no different! A low pressure system will track across the region over the next couple of days, bringing widespread 10-20cm to all three Prairie provinces by the end of the work week. What makes this storm more interesting is that while some areas could see up to 20cm of snow, others could see temperatures approaching 20°C, particularly in Southern Alberta and Southwest Saskatchewan!

The precipitation will begin Wednesday evening as rain across parts of Central Alberta. As the temperatures fall later in the evening, the rain will transition to snow, which will then spread both southward and eastward overnight and into early Thursday morning. A bit of rain will persist along the southern edge of precipitation into the morning, but it will eventually also transition over to snow, with a chance for some brief freezing rain in between.

Model Image showing the location and intensity of snow (Blue), Rain (Green), and Freezing rain (Pink) at 4AM MT Thursday

It’s during the early morning hours of Thursday that the snow will push into Saskatchewan while also starting to intensify across Central Alberta. As the morning continues, the heavy snow will cross into Saskatchewan, spreading southeastward across the province throughout the remainder of the morning and into the early afternoon. The snow will then spread into Southern Manitoba Thursday afternoon with the heavier snow beginning in the evening.

The heavy snow will fall for several hours, leading to rapid accumulation of up to 20cm across the region, with the possibility of pockets where up to 25cm could fall. The band of heavy snow will start to taper off early Friday morning, but light snow is expected to continue throughout the day, with the possibility of periods of heavier snow in both Saskatchewan and Manitoba.

Model Image showing the location and intensity of snow (Blue), Rain (Green), and Freezing rain (Pink) at 6PM CT Thursday

Wind gusts are expected to be up to 60km/h throughout the event and along with the heavy snow, travel may be difficult at times due to blowing snow. This could result in some isolated road closures in the hardest hit areas so make sure to check your local road conditions before going out over the next few days.

Up to 20cm of Additional Snow Expected With Second Storm of the Week

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The week of active weather continues in Maritimes with our second storm arriving late Wednesday, bringing a mixture of rain and snow to the region straight through to the end of the day Thursday.

This new system will move into Western Nova Scotia and Southwest New Brunswick Wednesday evening as mostly rain with a bit of snow. The precipitation with quickly spread eastward throughout the evening and subsequent falling temperatures will signal the beginning of the transition from rain to snow.

Model Image showing the location and intensity of snow (Blue), Rain (Green), and Freezing rain (Pink) at 2AM AT Thursday

After midnight, as the leading edge of the precipitation moves into Prince Edward Island, the snow will start to intensify in New Brunswick and Nova Scotia. The heavier snow will be somewhat scattered across New Brunswick, but it will be both more organized and heavier in Eastern Mainland Nova Scotia, Cape Breton Island and into Kings County, PEI.

The heavier snow is expected to persist through Thursday morning before tapering off in the early afternoon for Nova Scotia. Light snow is expected to continue in New Brunswick and PEI through the afternoon and evening, which will add a few more centimetres to the snowfall totals.

Eastern Nova Scotia, with the heaviest snowfall of the event, can expect up to 20cm by the end of the day Thursday. This will also be the case in eastern Kings County, PEI, while the rest of the Island can expect up to 10cm. Most of New Brunswick will see less than 5cm, but the heavier snowfall overnight, mixed with the lingering light snow throughout Thursday will drive totals up to 10cm in the east and into the Acadian Peninsula.

There’s the possibility of some brief snow on Friday that would only bring a couple of centimetres to the region and a significant storm on Saturday looks like it may stay offshore, but if that changes, we will provide updates!

⚠️ Significant Winter Storm Risk For Ontario This Weekend With Three Days of Freezing Rain Possible 🚨

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It may say spring on the calendar but Ontario could get a rude reminder that winter is not done with us quite yet! ❄️🥶 Environment Canada meteorologists are forecasting the potential for a significant winter storm this weekend that could bringing several days of freezing rain, causing icy roads, tree damage, and possible power outages across much of Southern Ontario.

*To clarify, “Southern” Ontario includes Southwestern, Central, Golden Horseshoe and Eastern regions. From many questions we’ve received, it seems that often ‘Southern Ontario’ is mistaken for ‘Southwestern Ontario’.

Meanwhile, lake effect snow will create hazardous travel conditions midweek, and this potentially significant winter storm could extend the icy mess into Sunday. Confidence remains low on exact snowfall amounts and ice accumulation, but this system looks like could pack a punch—stay prepared and watch for updates!

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📅 Tuesday, March 25, 2025

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📍 Location: Areas east of Lake Huron & Georgian Bay

🌨️ Hazard(s): Snow
📍 Location: Areas east of Lake Huron and Georgian Bay
⏳ Timing: Tuesday
⚠️ Impact(s): Hazardous travel conditions, reduced visibility

Confidence: Moderate
Impact: Moderate

🔹 Lake effect snow will develop early Tuesday morning with local snowfall amounts of 5 to 15 cm possible.

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📅 Wednesday, March 26, 2025

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📍 Location: Areas east of Lake Huron

🌨️ Hazard(s): Snow
📍 Location: Areas east of Lake Huron
⏳ Timing: Wednesday morning
⚠️ Impact(s): Hazardous travel conditions & Reduced visibility

Confidence: Low
Impact Level: Moderate

🔹 The lake effect snow will drift southward Tuesday night into Wednesday morning, with local snowfall amounts of 5 to 15 cm possible. Snow is expected to ease near midday.

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⚠️ Friday, March 28, 2025

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📍 Location: Portions of southwestern Ontario and the Greater Golden Horseshoe

🧊 Hazard(s): Ice
📍 Location: Portions of southwestern Ontario and the Greater Golden Horseshoe
⏳ Timing: Friday evening
⚠️ Impact(s): Icy surfaces such as roads and walkways

Confidence: Moderate
Impact Level: High

🔹 A prolonged freezing rain event is expected to begin Friday evening, with multiple waves of freezing rain. There is still uncertainty regarding the timing and exact location of the rain/freezing rain boundary. The freezing rain is expected to continue into the weekend for parts of southern, central, and eastern Ontario.

📍 Location: Northeastern, central, and eastern Ontario, as well as eastern portions of the Greater Golden Horseshoe

🌨️ Hazard(s): Snow
📍 Location: Northeastern, central, and eastern Ontario, as well as eastern portions of the Greater Golden Horseshoe
⏳ Timing: Friday evening
⚠️ Impact(s): Hazardous travel conditions & snow-covered and slippery roads/walkways

Confidence: Low
Impact Level: Moderate

🔹 Snow will push into the region Friday evening before clearing late Friday night or early Saturday morning. Snowfall amounts remain uncertain.

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📍 Location: Northwestern Ontario and western portions of the North Shore of Lake Superior

🌨️ Hazard(s): Snow
📍 Location: Northwestern Ontario and western portions of the North Shore of Lake Superior
⏳ Timing: Friday
⚠️ Impact(s): Hazardous travel conditions & snow-covered and slippery roads/walkways

Confidence: Low
Impact Level: Moderate

🔹 Heavy snowfall is expected Friday morning, persisting through the day before easing Friday evening. The heaviest snowfall areas remain uncertain.

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⚠️ Saturday, March 29, 2025

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📍 Location: Most of southern Ontario

⏳ Timing: Saturday
🧊 Hazard(s): Ice
📍 Location: Most of southern Ontario
⏳ Timing: Saturday
⚠️ Impact(s):

• ⚠️ Icy roads and walkways

• 🌳 Broken tree branches from ice build-up

• 🔌 Possible utility outages

Confidence: Too low in the extended range to assign a weather threat level
Impact Level: Potentially moderate or greater

🔹 A significant winter storm could bring an extended period of freezing rain, potentially leading to hazardous travel, minor tree damage, and power outages. Stay tuned for updates!

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⚠️ Sunday, March 30, 2025

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📍 Location: Most of southern Ontario

🧊 Hazard(s): Ice
📍 Location: Most of southern Ontario
⏳ Timing: Sunday
⚠️ Impact(s):

• ⚠️ Icy roads and walkways

• 🌳 Broken tree branches from ice build-up

• 🔌 Possible utility outages

Confidence: Too low in the extended range to assign a weather threat level
Impact Level: Potentially moderate or greater

🔹 A prolonged period of freezing rain is possible. Hazardous travel, tree damage, and power outages could occur. Stay alert for future updates!

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Final Thoughts:

A messy mix of snow and freezing rain is set to impact Ontario from Friday through the weekend, bringing travel hazards, icy conditions, and possible power outages. Uncertainty remains in the details but this system has the potential to cause significant impacts—stay tuned for updates!

TLDR; Be prepared for icy conditions, charge your devices, and take caution if you must travel. 🚗💨

Be safe, folks!

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Disclaimer: These forecasts are issued by Environment Canada and typically published via their Twitter/X accounts. We receive these forecast via a daily email and often publish them to help inform our communities.