First Isolated Severe Thunderstorm Risk of the Season for Parts of Southern Ontario Sunday Afternoon and Evening

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It’s certainly been a while since we’ve had an isolated risk for severe thunderstorm activity in Southern Ontario, but here we are! Welcome to Spring! What we’re expecting is a line of thunderstorms and based on the time I’m writing this (11:11am), it looks like it has already begun to develop over Lake Erie. This line will continue to push to the northeast, affecting the Niagara Region and potentially all the way up to Barrie and parts of Simcoe County.

RADAR IMAGE FROM 11:12 AM EDT - MAP FROM INSTANTWEATHER PRO

Taking a look at the IW Pro app screenshot above, you can see the thunderstorm line beginning to develop over Lake Erie. We’re expecting nickel-size hail (perhaps a bit larger), strong wind gusts, torrential rain and frequent lightning with this line. Additionally, you can see a red outline of a Tornado Watch south of the border that covers areas south of Lake Erie.

An isolated tornado cannot be entirely ruled out with this system slipping past the international border and tracking into Ontario, so we’ll be keeping a very close eye on radar today. If you don’t already have our free app, InstantWeather, today may be a good day to download it so we can notify you of any rotating storms, funnel cloud reports or Environment Canada alerts.

Some models have also shown some very intense wind gusts, potentially exceeding 100km/h, especially in eastern Ontario, so we’re fairly concerned with that potential. Being an early season event, we decided to go with a Marginal (green) risk, but there certainly is a chance these storms could exceed the Slight (yellow) threshold, especially with the wind risk.

MAX WIND GUST FORECAST FROM THE HRRR MODEL - MAP FROM WEATHERBELL

In the image above, we see the HRRR model’s maximum wind gust forecast for Southern Ontario, showing some very strong winds in yellow and orange. This is just one model’s output so it’s not a guarantee. Nonetheless, if wind gusts do reach these levels, even in isolated areas, we could end up seeing some fairly strong wind damage to trees, hydro polls or perhaps even structures.

The main risk, timing wise, should begin this afternoon in the Niagara Region, with storms moving northeast from Lake Erie and that risk should continue to spread northeast into the evening hours. Generally, our main concern is for Niagara and areas north and east of Lake Ontario into eastern Ontario. However, we have highlighted parts of Southwestern Ontario, the GTHA, and Central Ontario as well, as we’ve seen some model data suggesting strong wind gusts are possible in those regions, along with hail, torrential rain, isolated flooding, frequent lightning and a small risk of an isolated tornado.

In general, the tornado risk is quite isolated. Having said that, with a potent system south of the border, there is always a chance we could see some tornado activity sneak into Ontario and based on some of the model data we’ve seen over the past couple of days, the risk of a spin-up or two cannot be ruled out.

We do plan on doing a livestream if storms continue to look strong this afternoon and evening so make sure to subscribe to our YouTube channel in order to get notified if and when we go live!

We’ll be posting more updates to our social media pages as well so if you’re on Facebook, you can find us at Ontario Storm Watch. We also have a fantastic storm reporting group on FB with Ontario Storm Reports. And if you’re on X/Twitter, you can find us at @IWeatherON.

More details ASAP and stay safe today, folks!

- Adam

Mid-March Snowfall Will Help Build Back Some Snowpack With 10-20cm Expected Across a Wide Stretch of Alberta & Saskatchewan

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While we’re a little over a week away from the official start of spring, a majority of the snowpack is already gone across parts of Alberta and Saskatchewan. However, winter is still hanging on with more snow incoming over the next couple of days.

This will help to add some much-needed moisture to part of the region, especially since we have seen well below average snowfall since November. Unfortunately for Southern Alberta, the driest part of the Prairies, can expect little to none of this incoming moisture.

The snow will cross through the Rockies and into Alberta at around sunrise on Thursday and spread northeastward deeper into the province throughout the morning and into the afternoon. The snow will intensify starting in the early afternoon and this heavier snowfall will continue straight through overnight. This will lead to a large stretch of Central and Northern Alberta receiving 10-20cm of snow and up to 25cm possible to the north of Lake La Biche and Cold Lake through Friday morning.

Model Image showing the location and intensity of snow (Blue) and Rain (Green) at 4PM MT on Thursday

Light snow will make its way into Northern Saskatchewan early Thursday afternoon, followed by the more intense snowfall beginning in the early evening. This area of heavier snow will cross through Saskatchewan in an almost due easterly path and similar to in Alberta, it will dump 10-20cm across a large stretch of the province and up to 30cm from the Alberta border to almost La Ronge by Friday afternoon.

The arrival of additional moisture from a separate low-pressure system in the US on Friday morning makes the forecast in Central and Southern Saskatchewan a bit more complicated. This appears to be bringing a combination of rain, freezing rain, ice pellets, and snow to most of the southern half of the province throughout the morning as it merges with the system from the west.

There is still some uncertainty regarding the precipitation type and the area that could be impacted by the arrival of the secondary system. Therefore, for this forecast, we are only focusing on the snow coming from Alberta and we will cover this additional precipitation in a separate forecast that will be issued later in the day on Thursday

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (pink), and ice pellets (orange) at 2aM MT on Friday

Total Lunar Eclipse Alert: Rare Blood Moon Visible Across Ontario on Thursday Night

Image of a total lunar eclipse/blood moon

On the night of Thursday, March 13, 2025, into the early hours of Friday, March 14, Ontario residents will have the opportunity to witness a spectacular total lunar eclipse, often referred to as a “Blood Moon.” 

What to Expect

During a total lunar eclipse, the Earth comes directly between the Sun and the Moon, casting a shadow that gives the Moon a reddish hue. This phenomenon occurs as Earth’s atmosphere filters out shorter-wavelength blue light, allowing the longer-wavelength red and orange light to illuminate the Moon’s surface.

Key Times for Ontario

Eastern Daylight Time

• Start of Penumbral Eclipse: 11:57 PM on Thursday, March 13

• Start of Totality: 2:26 AM on Friday, March 14

• Maximum Eclipse: 2:58 AM

• End of Totality: 3:31 AM

• End of Penumbral Eclipse: 6:00 AM

The totality phase, when the Moon is entirely within Earth’s shadow and appears deepest red, will last approximately 1 hour and 5 minutes. 

Viewing Tips

• No Special Equipment Needed: Lunar eclipses are safe to observe with the naked eye. However, using binoculars or a telescope can enhance the experience by providing a closer view of the Moon’s surface.

• Optimal Viewing Locations: Find a dark area away from city lights to reduce light pollution. Elevated spots with an unobstructed view of the sky are ideal.

• Weather Considerations: Check local weather forecasts to ensure clear skies during the eclipse. Partly cloudy conditions may still allow for intermittent viewing.

TOTAL CLOUD COVER ON FRIDAY MORNING - MAP FROM WEATHERBELL

Viewing Conditions Across Ontario

• Southern Ontario: Forecasts indicate mostly clear skies throughout the eclipse period, providing optimal viewing conditions. However, some areas may experience pockets of partly cloudy skies, so it’s advisable to monitor local forecasts as the event approaches. Download our free app for your local forecast.

• Northern Ontario: Regions, especially Northwestern Ontario and areas around Lake Superior, may encounter heavy cloud cover, potentially obstructing the view of the eclipse. Residents in these areas should check local weather updates for the most accurate information.

Photography Tips

• Use a Tripod: To capture clear images, stabilize your camera to prevent blurring during long exposures.

• Adjust Exposure Settings: Since the Moon will be dimmer during totality, longer exposure times and higher ISO settings may be necessary.

• Practice Prior to the Eclipse: Familiarize yourself with your camera’s settings and practice shooting the Moon on clear nights leading up to the event.

More Freezing Rain & Snow in Store, Potential for Flash Freeze Across the Maritimes on Friday

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The moisture-laden Colorado Low that has brought a mixed bag of precipitation to the Maritimes over the past two days appears to have one last trick up its sleeve. Cold air will flood into the region overnight, transitioning the rain over to snow and bringing some further complications.

In New Brunswick, the rain will start to switch over at around 1-2AM, however there will be a couple of hours of freezing rain in Central and Northern New Brunswick once again before the change over to snow. The heaviest snow is expected to fall in Carleton and Victoria Counties and northward into Madawaska and parts of Restigouche. This region can expect 10-20cm of snow by Saturday morning and the possibility of locally higher amounts, particularly in Madawaska County. Much of the rest of the province will see 5-10cm, with the exception of along the Fundy Coast and into the Southeast and Moncton area, where less than 5cm is anticipated.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 5AM AT Friday

In Western Nova Scotia, the rain will taper off in the early morning hours of Friday, but it will be replaced by snow starting at around 8-9AM. The snow will be light and short-lived for much of the western half of the Mainland, but it will remain fairly steady in the Annapolis Valley through the afternoon and into the evening, leading to 5-10cm by the end of the day.

Across the rest of Mainland Nova Scotia, snowfall will be light and scattered as the band of snow makes its way across the province, leading to up to 5cm. The snow will eventually begin in Cape Breton late Friday evening, where it will continue through to Saturday morning. Most of the Island can expect 5-10cm, with lesser amounts around Sydney and up to 20cm in the Highlands.

The snow in Prince Edward Island, like in most of Nova Scotia, will also be very light and patchy. It will reach the province in the evening and the scattered flurries will continue into Saturday morning, leading to up to 5cm across the Island.

Modelled Temperatures at 9PM Thursday

Modelled Temperatures at 1PM Friday

The drop in temperatures that will cause the transition from rain to snow has another considerable implication. Temperatures are expected to plummet to several degrees below freezing across the region, after climbing into the double digits Thursday, and when combined with the preceding rain and melt-water, most of the Maritimes is under the threat of a flash freeze occurring on Friday.

This potential flash freeze could lead to wet, untreated surfaces quickly becoming icy and making travel hazardous as the temperatures drop across the region. Adding a layer of snow on top of this ice will keep things quite slippery as well.

The winds are expected to pick up on Friday, gusting up to 70km/h through most of the afternoon and then as high as 100km/h beginning in the evening and continuing for most of Saturday. These strong winds will likely reduce visibility due to blowing snow, both during and after the snow has stopped falling, and possibly lead to localized power outages.

Threat of Localized Flooding & Freezing Rain Risk in New Brunswick with the Arrival of a Winter Storm Wednesday

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A Colorado Low is set to move through the Maritimes this week, bringing a mixture of rain, freezing rain, and snow to the region, along with the risk of flooding as temperatures rise.

Brief light snow will begin in Southwestern New Brunswick at around sunrise on Wednesday, spreading northeastward into the province throughout the morning and early afternoon. There is a chance for some freezing drizzle around Saint John mixed with the snow. Meanwhile in Nova Scotia, the precipitation will fall as rain across much of the western half of the province, aside from some light snow expected in Northern Nova Scotia.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 1PM AT Wednesday

By the mid-afternoon, the bulk of the moisture from the system will push eastward into the region, bringing rain to Nova Scotia and Southern New Brunswick while Central and Northern New Brunswick will start to receive snow. The precipitation will reach PEI later in the afternoon as a mix of rain and snow across the Island.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 12AM AT Thursday

Starting in the evening, the warm air and rain will start to push northward, leading to a transition from snow to a few hours of freezing rain across Central and Northern New Brunswick, as well as into PEI and Cape Breton. The freezing rain will continue overnight and into early Thursday morning. Ice accretions of up to 5mm are likely, but buildup will be short-lived as the temperatures will continue to rise and the freezing rain will switch over to rain for the remainder of Thursday.

Ahead of the transition to freezing rain and rain, up to 10cm of snow will fall, with the highest amounts expected in Retigouche County and into the Acadian Peninsula.

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Not only will the fresh snowfall melt with the rain and temperatures climbing into the double digits on Thursday, but a considerable amount of pre-existing snowpack, especially across New Brunswick will also melt. Parts of Central and Northern New Brunswick have over 70cm of snow on the ground as of Tuesday evening and that value is expected to drop to below 50cm in some areas by Friday. Similarly, Moncton and Saint John, where 10-20cm is already on the ground, could see most, if not all, of their snow melt.

This rapid melting of the snow, along with some heavy rain expected later in the day on Thursday, has led to a significant flooding threat across New Brunswick. The ground is still frozen and recent frigid temperatures have led to ice buildup on lakes and rivers, which will limit where the water from the snow melt and rain can go.

The situation in Nova Scotia and into PEI is less widespread with lesser snowpack overall. There are some areas in Nova Scotia that have up to 30cm of snow on the ground that will almost completely melt, namely in the Annapolis Valley and in Cumberland and Colchester Counties. Those in Cape Breton can expect to see some of their snowpack melt, but the Highlands will experience very little change. In Prince Edward Island, on the other hand, next to no snow will remain on the Island come Friday aside from pockets of up to 5cm possibly remaining in Prince and/or Kings Counties.

The modelled depth of snow across Atlantic Canada, in centimetres, as of 8pm Tuesday.

Winter Returns to Ontario as End of Week Clipper Brings Widespread 10-20cm of Snow for the Start of March

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The first half of February has been nothing short of active across Ontario, with what felt like an endless stream of snowstorms dumping significant amounts of snow across many areas.

Fortunately, the latter half of the month provided a much-needed break from the active weather pattern. Milder temperatures pushed daytime highs above the freezing mark, leading to a steady melt of the extensive snowpack that had built up over previous weeks.

However, as the saying goes, all good things must come to an end. As we flip the calendar to March, active weather is set to make a comeback. A strong Alberta Clipper is on track to sweep across Northern and Southern Ontario on Friday, bringing widespread snowfall totals of 10 to 20 cm by Saturday.

In addition to the snow, this system will usher in much colder temperatures for the weekend. Wind chills are expected to drop into the -20s across Southern Ontario, while Northern Ontario will see even more bitter conditions, with wind chills dipping into the -30s. This will feel like a drastic change compared to the mild temperatures earlier this week, when parts of Southern Ontario saw highs in the mid to upper single digits.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The first signs of the approaching clipper will be felt in Northwestern Ontario late Thursday night into early Friday morning, as snow spreads in from Central Manitoba.

Locations like Kenora, Dryden, and Thunder Bay will be the first to see snowfall, beginning around midnight and continuing into the early morning hours.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

As the system moves eastward, snow will taper off across Northwestern Ontario by late Friday morning, while the heaviest snowfall shifts to Northeastern Ontario, particularly around Lake Superior and Georgian Bay.

By this time, we’ll also begin to see light snow entering Southwestern Ontario, particularly around Lake Huron, which will become more widespread as the day progresses.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By Friday afternoon, snow will spread into Southern Ontario, becoming more steady across the Greater Toronto Area (GTA).

The heaviest accumulations will likely be concentrated along the Lake Huron and Georgian Bay shorelines, particularly in Grey-Bruce, Muskoka, and Parry Sound. Lake enhancement in these areas could provide an extra boost to snowfall totals.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

The worst conditions for Southern Ontario will occur Friday evening, when snowfall rates could reach 2 to 4 cm per hour in the most intense bands. The snow will be widespread, impacting Central and Eastern Ontario, the GTA, and Grey-Bruce.

Additionally, blowing snow may become a significant issue, as wind gusts of 40 to 70 km/h could reduce visibility on the roads.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By midnight, snowfall intensity will begin to gradually diminish, and most areas southwest of Lake Simcoe—including the GTA—should see snow tapering off. However, lake-effect snow east of Lake Huron may continue into the overnight hours.

Meanwhile, light snow will persist overnight across Central and Eastern Ontario, but it is expected to slowly taper off by Saturday morning.

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In terms of Alberta Clippers, this one appears to be on the stronger side, with a fair amount of moisture to work with. While it will be fast-moving, we are still expecting widespread snowfall totals between 10 to 20 cm across much of Central and Eastern Ontario by Saturday morning.

Some areas could overachieve, with up to 25 cm possible, especially in regions east of Georgian Bay, where lake enhancement could further boost totals.

Further south, including areas like Goderich, Kitchener, Toronto, Peterborough, and Kingston, lower snowfall amounts are expected. While these regions will still see fresh snow, totals will likely range between 5 to 10 cm due to lower snowfall rates compared to areas further north.

For Deep Southwestern Ontario, including London and the Niagara region, snowfall will be minimal, with less than 5 cm expected.

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Across Northern Ontario, a wide swath of the region is on track to receive 10 to 20 cm from this system, including Dryden, Thunder Bay, Sault Ste. Marie, Timmins, Sudbury, and North Bay.

As with the south, there is potential for some areas to overperform, particularly east of Lake Superior, where localized totals of up to 25 cm are possible.

With accumulating snow, strong winds, and plummeting temperatures, this clipper will bring notable impacts heading into the weekend. Stay tuned for further updates as the system approaches!

Quick Blast of Intense Snowfall Could Bring Over 20cm to Parts of Saskatchewan and Manitoba

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February has been a quiet month across the Prairies, as far as active weather is concerned. That has changed though, with the arrival of warmer air in the past few days, which has also brought heavier snowfall back to the region. Now, we are looking at that heavy snow across Saskatchewan and Manitoba for Thursday and Friday.

The snow will begin early Thursday in Northern Saskatchewan and surge southeastward throughout most of the morning, crossing into Manitoba at around 8-9am. The snow will be steady and fairly light for most of the day, falling at up to 2cm/hr, leading to a large swath of over 10cm across both provinces.

In the late afternoon and early evening, the snow will begin to taper off in Saskatchewan while at the same time, intensifying in Central Manitoba. The heavier snow is expected to cross the province throughout the evening and will bring snowfall totals to the higher end of the 10-20cm range, with a strong likelihood of localized pockets of over 20cm, particularly around Flin Flon, The Pas and Norway House. The intensified snowfall will also be associated with some stronger wind gusts of up to 70km/h, which could result in isolated whiteouts due to blowing snow.

As the short-lived system exits the region, the snow will finally taper off in Saskatchewan shortly after midnight on Friday and in Manitoba just before sunrise. The winds are also expected to weaken Friday morning, therefore reducing the blowing snow risk.

Snow Squalls Target the Grey-Bruce and Barrie Area Again With Locally Up to 50-100cm of Snow by Tuesday

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Snow squalls are expected to become well-organized and intensify by Monday morning. One squall off Lake Huron will target southern Grey-Bruce, with periods of intense snowfall throughout the day. Thundersnow is even a possibility in this area.

Another squall will develop off the southeast shoreline of Georgian Bay, impacting parts of southern Simcoe County, including Wasaga Beach, Barrie, Angus, Innisfil, and Keswick.

These squalls will persist into the afternoon, shifting at times. The northern squall could push into Wiarton, extend across Georgian Bay, and come onshore near Barrie. Meanwhile, the southern squall off Lake Huron will stretch from Kincardine to Hanover and could push far inland, periodically bringing heavy snow into parts of the GTA.

By Monday night into Tuesday morning, the Lake Huron squall is expected to stall over southern Grey-Bruce, potentially leading to extreme snowfall accumulation. Wherever this band locks in, snowfall rates could reach an incredible 5-10 cm per hour. Some models suggest this squall could remain in place until Tuesday evening, somewhere between Owen Sound and Hanover.

The Georgian Bay squall may weaken somewhat after midnight but could persist into Tuesday. All snow squall activity should fizzle out by early Wednesday morning.

Projected Snowfall Totals:

• Localized amounts near 100 cm are possible in Grey-Bruce, with hotspots likely near Port Elgin, Hanover, Chatsworth, and Flesherton. Not everyone in this zone will see these totals, but some areas will get buried.

• 25 to 50 cm is likely across the rest of Grey and Bruce counties, extending into northern Huron and Perth counties. This also includes areas along the southeastern shoreline of Georgian Bay, such as Collingwood, Wasaga Beach, and Barrie.

• 5 to 15 cm could extend into Kitchener, Guelph, Durham, and York as occasional bursts of heavy snow push outside the core snowbelt region.

• The GTA may see light snow at times but is unlikely to receive more than 5 cm over the next two days.

Aside from the snow, we’re starting the week on a much colder note. If you’re heading outside for Family Day, be sure to bundle up—wind chills in the -20s are expected on Monday.

Stay safe and stay warm!

Strongest Snowstorm in Years to Bury Southern Ontario in Up to 50cm of Snow on Sunday

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Brace yourself, Southern Ontario! One of the biggest snowfalls in recent years is on the horizon for many parts of the region—excluding the usual snowbelt areas. This includes major cities like Toronto, Kingston, and Ottawa, which have largely dodged significant snowstorms over the past few years due to milder winters.

That streak ended earlier this week with the first storm in this parade of systems, dropping a widespread 20 cm or more across Southern Ontario. However, that system could pale in comparison to what’s coming next. This stronger storm is likely to bring 30 cm or more to a large portion of the region throughout Sunday.

As of Saturday afternoon, the first round of snow has already arrived, bringing steady snowfall from Southwestern Ontario into the Golden Horseshoe. This initial wave will be just the beginning, with up to 10 to 15 cm expected by the end of the day.

The second and much more intense round of precipitation will begin early Sunday morning as the system taps into tropical Gulf moisture and directs it straight into the Great Lakes region.

By morning and into the afternoon, conditions will deteriorate rapidly, with snowfall rates reaching 4 to 8 cm per hour. When combined with moderately strong wind gusts, this will lead to widespread blowing snow, significantly reduced visibility, and even localized blizzard conditions.

By the time the snow begins to taper off late Sunday, widespread totals of 30 to 50 cm are expected across Central and Eastern Ontario, extending into the Greater Toronto Area. The hardest-hit areas could even exceed 50 cm, particularly in Eastern Ontario, where elevation may enhance accumulation. Meanwhile, locations along the Lake Erie shoreline, including Windsor, Niagara, and Chatham, may see lower snowfall totals due to potential mixing with freezing rain or ice pellets.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The first round of snow will continue steadily across Southern Ontario through Saturday evening and past midnight, with heavier snowfall targeting the Golden Horseshoe and the southern portions of Central and Eastern Ontario.

At the same time, the second round of snow will be rapidly developing south of the Great Lakes, forming over Indiana, Kentucky, and Ohio. This storm will strengthen quickly as it begins pulling in moisture from the Gulf of Mexico, which is also fueling severe thunderstorms across the southern U.S.

While there may be a brief lull overnight, don’t let it fool you—the worst is still ahead. The heaviest snowfall will begin to push into Southwestern Ontario before sunrise, bringing a rapid increase in snowfall rates from 1 to 2 cm per hour earlier in the night to 2 to 4 cm per hour by the early morning.

As the system intensifies, hourly rates of 4 to 6 cm—potentially even higher in the strongest bands—are expected. Road conditions will deteriorate quickly, with significantly reduced visibility and heavy blowing snow making travel extremely hazardous.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Most areas will remain on the snowy side of this system, but there is some uncertainty regarding how far north a warm layer could push. This could lead to a brief period of ice pellets or freezing rain in areas along the Lake Erie shoreline, including Windsor, Leamington, Chatham, St. Thomas, Tillsonburg, Hamilton, and Niagara Falls.

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While significant freezing rain is not expected, some minor ice accretion of a few millimetres could occur, particularly right along the shoreline.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

By early to mid-morning Sunday, the storm’s intensity will peak across Southwestern Ontario and the GTA, with snowfall rates reaching 4 to 6 cm per hour in many areas. In the strongest bands, these rates could climb even higher, creating whiteout conditions.

Wind gusts of 40 to 60 km/h will further reduce visibility, and there is even the possibility of thundersnow as some of these snow bands intensify.

Meanwhile, areas farther north, including regions around Lake Simcoe, Peterborough, and into the Ottawa Valley, will begin to see snowfall intensities climb to 1 to 2 cm per hour, eventually reaching 5 to 10 cm per hour by the early afternoon

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

The later part of Sunday morning after sunrise will see the worst conditions through Southwestern Ontario into the GTA as snowfall rates increase even further towards 4 to 6cm and possibility even higher in the strongest pockets of snow.

This snow will also be accompanied by increasing wind gusts near 40 to 60 km/h leading to blowing snow and blizzard conditions. Don’t be surprised to see some thundersnow during the morning as these bands of snow will be quite strong and could produce some lightning as they move through the region.

Snowfall intensity will also gradually increase through Central and Eastern Ontario with hourly snowfall rates reaching 1-2cm per hour around Lake Simcoe through Peterbough and into the Ottawa Valley.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

As the system continues to push eastward, the most intense snowfall rates will shift into Central and Eastern Ontario. This is when travel will become nearly impossible in these areas as plows struggle to keep up with the rapid accumulation.

For Southwestern Ontario and the GTA, conditions will begin to improve slightly in the afternoon as the heaviest snow moves east. However, steady snowfall of 1 to 3 cm per hour will continue through much of the afternoon, with strong winds still blowing around earlier accumulations and keeping visibility low.

Snow will gradually taper off across Central and Eastern Ontario by Sunday evening, but blowing snow will remain a significant issue overnight. Travel will remain difficult even after the snowfall ends, particularly in areas with open terrain where drifting will be an issue.

By Monday, conditions should improve, but significantly colder air will move in. If possible, clearing snow on Sunday before temperatures drop is strongly recommended, as the snow will become much heavier to shovel once it settles and freezes.

ESTIMATED WIND GUSTS - MAP FROM WEATHERBELL

The strongest wind gusts will be found in Eastern Ontario, peaking during the early to mid-afternoon. Widespread gusts of 50 to 70 km/h are expected, with some areas, particularly around Ottawa and to the east, possibly seeing gusts near 80 km/h.

In comparison, the rest of Southern Ontario, including the Golden Horseshoe, will experience gusts of 40 to 60 km/h, while Southwestern Ontario will likely see gusts under 40 km/h.

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These wind speeds combined with the extreme snowfall rates expected across Eastern Ontario will almost certainly lead to blizzard conditions.

For a storm to meet the official criteria for a blizzard, winds of 40 km/h or greater must cause widespread reductions in visibility to 400 meters or less due to blowing and falling snow for at least four consecutive hours.

Based on current model data, it is highly likely that visibility will remain near zero for at least six hours from late morning to early/mid-afternoon in many parts of Eastern Ontario, surpassing the official blizzard threshold.

While it remains uncertain whether areas such as the GTA, Lake Simcoe, and Muskoka will officially reach blizzard criteria, blowing snow will still cause significant travel disruptions regardless of classification.

Regardless of whether your area officially meets blizzard criteria, this storm will create extremely dangerous travel conditions across much of Southern Ontario throughout Sunday.

Roads will become impassable at times, and even major highways will be difficult to navigate. Plows will struggle to keep up with the rapid accumulation, making travel nearly impossible in the worst-hit areas. If you don’t absolutely need to be on the roads, it is strongly advised to stay home.

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By the time the storm ends, the highest snowfall totals will be found across Central and Eastern Ontario, extending into portions of the GTA, with widespread accumulations ranging from 30 to 50 cm. Some areas, particularly in Eastern Ontario near Ottawa and through higher elevations to the west, could exceed 50 cm.

Regions around Lake Simcoe and the northern GTA will likely end up with 30 to 40 cm, though locally higher amounts are possible in areas such as the Dundalk Highlands. The Hamilton region and western GTA may see slightly lower totals, around 20 to 30 cm, due to the potential for ice pellets mixing in at times.

Southwestern Ontario, particularly along the Lake Huron shoreline, will see slightly less snowfall, with totals ranging from 20 to 30 cm. This includes areas such as Sarnia, London, Goderich, Grey-Bruce, Parry Sound, and North Bay. However, if the system strengthens earlier than expected, some of these locations could still exceed 30 cm.

Meanwhile, the lowest totals will be found along the Lake Erie shoreline, including Windsor, Chatham, and the Niagara region, where snowfall will range from 10 to 20 cm.

Looking ahead, colder temperatures are expected to settle into Southern Ontario by Monday. It would be wise to clear as much snow as possible on Sunday before the deep freeze sets in, as the snow will become significantly harder to move once temperatures drop.

Additionally, this colder air may trigger a resurgence of lake-effect snow early next week, which could lead to further significant snowfall accumulations in the typical snowbelt regions around Lake Huron and Georgian Bay. More details on that will come in a separate forecast.

This storm will be a major event, and conditions will be dangerous. If possible, stay home and avoid travel. We will continue to monitor the latest data and provide updates as needed. Stay safe!

Intense Snowstorm Could Bring Blizzard Conditions and Up to 30-60cm of Snow to Southern Ontario This Weekend

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The snowy weather isn’t letting up as yet another winter storm takes aim at Southern Ontario over the Family Day long weekend. This system will arrive in multiple waves, beginning Saturday and continuing through Sunday. By the time it moves out late Sunday, much of Southern Ontario could be buried under as much as 60 cm of snow.

Strong winds will develop throughout Sunday morning into the afternoon, with gusts reaching 50 to 80 km/h in some areas. These powerful winds, combined with heavy snowfall, will create dangerous whiteout conditions and may even reach blizzard criteria. Travel is expected to become difficult as early as Saturday morning, with conditions steadily worsening through the night and into Sunday.

The most hazardous conditions are expected Sunday morning and afternoon, as intense snowfall rates are combined with strong wind gusts, making all non-essential travel extremely dangerous. Highway closures are highly likely in the hardest-hit regions as plows struggle to keep up with rapid snowfall rates, while blowing and drifting snow significantly reduces visibility.

There is still some uncertainty regarding the storm's exact track, which will determine where the heaviest snowfall occurs. Areas along the Lake Erie shoreline and possibly parts of the Golden Horseshoe could see periods of freezing rain or ice pellets by late Sunday morning. While this would create its own hazards, any mixing would also lower overall snowfall totals.

As of now, Eastern and parts of Central Ontario appear to be in line for the highest snowfall amounts. Combined two-day snowfall totals could range from 30 to 60 cm by Sunday night, with 5-10 cm expected on Saturday and an additional 25-50 cm possible on Sunday.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

The storm will get underway Saturday morning as steady snow moves into Deep Southwestern Ontario from Michigan. It will spread into London and the Greater Toronto Area (GTA) by late morning. Some light flurries may reach Central and Eastern Ontario, but the more persistent snowfall will remain south of Lake Simcoe.

At this stage, conditions may not seem too severe, leading to the false impression that the storm has been overhyped. However, don’t be fooled—snowfall rates will gradually increase through the afternoon, reaching 1-2 cm per hour and steadily accumulating.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

By mid-afternoon Saturday, light to moderate snowfall will have spread across most of Southern Ontario. The heaviest snowfall will be concentrated over Southwestern Ontario and the GTA, while Central and Eastern Ontario, including the Ottawa Valley, may only see scattered flurries.

There are indications that parts of Deep Southwestern Ontario—including Windsor, Chatham, and possibly London—may see a transition to ice pellets or freezing rain. Meanwhile, Kitchener, Hamilton, and the GTA should remain primarily snow.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

Heading into the evening, the storm’s moisture supply will intensify as it taps into the Gulf of Mexico, keeping snow steady across Southern Ontario. However, Central and Eastern Ontario may experience more scattered snowfall during this time. The most persistent snow bands are expected to set up along the Windsor-London-Hamilton corridor.

Some mixing could still occur near the Lake Erie shoreline, particularly in Leamington and the southern Niagara region, though it remains uncertain how far inland it may extend. If the mixing line pushes north, areas such as Windsor could also see freezing rain.

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By the end of Saturday, snowfall totals are expected to range from 5 to 10 cm across much of Southern Ontario, with locally higher amounts of up to 15 cm in areas benefiting from lake enhancement like Southwestern Ontario and the Golden Horseshoe.

Eastern Ontario and the Ottawa Valley will see lower totals, between 2 and 5 cm, as the first wave of snow stays focused farther south.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Conditions will deteriorate rapidly overnight Saturday as even more moisture-laden precipitation moves in from Michigan. Snowfall rates will increase during the pre-dawn hours, starting in the southwest around midnight before progressing east and north through the morning.

There remains some disagreement among forecast models regarding the extent of mixing along the Lake Erie shoreline, but there is a possibility of significant ice accretion in parts of Windsor and the Niagara region.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By late Sunday morning, the system is expected to intensify rapidly as the low-pressure center tracks south of the Great Lakes. This intensification will result in significantly higher snowfall rates, especially in the GTA, Niagara region, and Central Ontario, including Barrie, Muskoka, and Peterborough.

Snowfall rates could reach 5-10 cm per hour, making it impossible for road crews to keep up. Eastern Ontario and the Ottawa Valley will see steady snow increase throughout Sunday afternoon and into the early evening.

ESTIMATED WIND GUSTS - MAP FROM WEATHERBELL

Adding to the severity of the storm, strong wind gusts of 50-80 km/h will develop through Sunday morning, with the highest gusts expected in Central and Eastern Ontario. These winds, combined with intense snowfall rates, will almost certainly lead to blizzard conditions in some areas.

Visibility will be near zero, with blowing and drifting snow making travel dangerous. All non-essential travel should be avoided on Sunday morning and afternoon, as highway closures are likely in the hardest-hit regions. With snow falling at rates of 5-10 cm per hour, it will be extremely easy to become stranded, as plows will struggle to keep roads passable.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Despite being less than 48 hours away, there is still some uncertainty in the storm's track and timing. Different forecast models continue to show varying scenarios, which could impact snowfall totals and the extent of mixing.

The short-range American model (HRRR), which provides detailed hourly forecasts, aligns closely with the Canadian and European models. These models suggest a more southern track, keeping the GTA and much of Southern Ontario primarily in the snow zone.

However, another American model (NAM) suggests a more northern track with a later arrival. If this scenario plays out, the mixing line would shift farther north, bringing ice pellets or freezing rain from London to Hamilton and into the GTA. This would reduce snowfall totals in these areas but create hazardous icy conditions.

This model also suggests the mixing could extend along the Lake Ontario shoreline into parts of Southeastern Ontario, including Belleville, Kingston, and Brockville. While this scenario is less likely, it’s still worth monitoring.

Additionally, the NAM model points to a significant icing event for Hamilton and the Niagara region, with potential ice accretion of 10-15 mm. If this happens, localized power outages and tree damage could occur.

The model also suggests that while some forecasts indicate the heaviest snow will arrive early Sunday, this scenario shifts the worst conditions to the afternoon in Southwestern Ontario and the GTA, extending into the evening for Eastern Ontario.

Regardless of the final track, conditions should improve as snow tapers off from west to east late Sunday evening, with lingering snow in Eastern Ontario into early Monday morning. However, lake-effect snow could quickly develop around Lake Huron and Georgian Bay as the system exits.

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By the time this storm is over, a wide swath of Eastern and Central Ontario could see 30-60 cm of fresh snow, including the accumulation from both Saturday and Sunday.

For Southwestern Ontario and the GTA—including Sarnia, London, Kitchener, Hamilton, and Toronto—snowfall totals will likely range from 20-40 cm. However, if mixing occurs on Sunday, snowfall amounts could drop to 15-30 cm or even lower, depending on how extensive the ice pellets or freezing rain become.

The lowest snowfall totals will likely be in Deep Southwestern Ontario and along the Lake Erie shoreline, where freezing rain and ice pellets will reduce overall accumulation. Areas such as Windsor, Leamington, Chatham, St. Thomas, and Niagara Falls could see between 15-30 cm of snow, depending on how much mixing occurs.

We are closely monitoring the latest forecast data and will provide a more detailed breakdown of Sunday’s snowfall totals in an updated forecast on Saturday. Stay tuned for further updates.

Another Major Winter Storm Looks to Make a Mess of the Maritimes This Weekend

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The latest storm is barely in our rear-view mirror and we’re already looking ahead to the next one. This incoming storm, with a projected track that keeps shifting considerably over the span of a few hours between weather model runs, is slated to hit the Maritimes on Sunday and continue through most of Monday.

Similar to the storm that just hit the region, the next storm will bring a range of precipitation types due to the presence of warm air. Unfortunately, the amount of precipitation with this next storm is expected to be much greater and current projections show up to 60cm of snow possible in Northern New Brunswick and over 10mm of ice accretion across parts of Nova Scotia, PEI, and into Southern New Brunswick.

At this point, there is still some considerable uncertainty regarding the timing, precipitation types and the amount of each expected locally. This will be dependent on the exact path the storm will take as it makes its final approach into the region and how far north the warm air aloft will extend. We hope to have greater clarity of the situation over the next 24 hours and we will provide more details ASAP.

Precipitation Types with temperature profiles

Will It Ever End? Squalls Could Bring Up to Another 40cm of Snow by the End of Friday to Parts of Southern Ontario

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Are you enjoying winter yet, Ontario? ❄️ It feels like we've been stuck in an endless cycle of snow, with relentless snow squalls hammering the snowbelt regions.

Even outside the snowbelts, much of Southern Ontario joined in this week as a major winter storm dumped over 20 cm of snow across the region overnight into Thursday morning.

And the snowy pattern isn’t letting up anytime soon. More lake effect snow is on the way to end the week, followed by a potentially significant snowstorm this weekend.

The lake effect machine is expected to fire back up Thursday evening, becoming more organized overnight into Friday morning. Current indications suggest a strong snow squall will develop, targeting the Bruce Peninsula and stretching into parts of Simcoe County.

While squall activity should begin to wind down by Friday afternoon, areas that have already been hit hard this season—such as Orillia, Midland, Wiarton, Lion’s Head, and Tobermory—could see another 15 to 25 cm of snow. If the squall locks into place for an extended period, localized totals of up to 40 cm are possible.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

As of early Thursday evening, bands of lake effect snow are already forming off Lake Huron and Georgian Bay. These will continue to shift around throughout the evening, delivering bursts of heavy snowfall to different areas.

Right now, it looks like the heaviest snowfall will be concentrated across the Bruce Peninsula and along the southeastern Georgian Bay shoreline, including Collingwood, Barrie, Angus, and Keswick. Additional, weaker bands may impact regions east of Lake Huron, from Owen Sound to Goderich.

By midnight, models suggest that a narrow but intense squall could set up, stretching from the Bruce Peninsula, over Georgian Bay, and into Barrie. However, there’s still uncertainty about its exact strength and how stationary it will be overnight. Some models show it drifting north toward Midland and Orillia, while others keep it in place longer.

If the squall aligns just right, it could connect with both Lake Huron and Georgian Bay, allowing it to tap into additional moisture. This could make it stronger than expected, potentially bringing more snow to Barrie than initially forecasted. Right now, Barrie sits right on the edge between significant snowfall and minimal accumulation.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By Friday morning, the squall will likely continue hammering the Bruce Peninsula and Simcoe County but may have shifted slightly north, putting Tobermory, Midland, and Orillia in the bullseye for heavy snow during the late morning.

Depending on its strength, the squall could even extend into portions of Durham and the Kawartha Lakes at times. This squall may remain stationary for several hours, with snowfall rates reaching 5-10 cm per hour.

It won’t take long for roads to become impassable, especially along the Highway 400 and Highway 11 corridors. Plows will struggle to keep up with such intense snowfall rates, and whiteout conditions will make travel extremely dangerous. If you can, stay home—this is the kind of snow that can lead to major travel disruptions and accidents.

By early Friday afternoon, the squall should gradually weaken as winds shift and become less favourable for lake effect snow.

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As with any lake effect event, snowfall totals will be highly variable, depending on where these narrow snow bands set up.

The hardest-hit areas are expected to be across the Bruce Peninsula, including Tobermory, Lion’s Head, and Wiarton, extending into Simcoe County in areas like Midland, Washago, and Orillia. These regions could see 15 to 25 cm, with localized totals near 40 cm possible in central Simcoe County, closer to Georgian Bay.

Surrounding areas—including Grey-Bruce, Huron, and Perth counties east of Lake Huron—could see 5 to 15 cm, though some spots may see little to no snow due to how localized these bands are. Southern Muskoka, portions of Kawartha Lakes, and Durham Region may also receive up to 5 to 10 cm in some areas.

The rest of Southern Ontario should see less than 5 cm of snow over the next 24 hours, as the lake effect snow stays confined to the snowbelt regions.

While the lake effect snow wraps up Friday, a much bigger storm could be on the way this weekend. A potential multi-day snowfall event is on track to begin Saturday, and continue into Sunday.

Right now, there’s still uncertainty regarding snowfall totals and the exact timing of the worst conditions, but early indications suggest that much of Southern Ontario—particularly Eastern Ontario and the Golden Horseshoe—could see 20-30 cm or more by the end of the weekend.

We’re waiting on the latest model data this evening and will have a preliminary forecast on this potential snowstorm later today or early Friday. Stay tuned!

Strong Winter Storm Expected to Bring Over 30cm of Snow and Prolonged Freezing Rain to the Maritimes

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The winter storm that we’ve been tracking is bearing down on the Maritimes and things are going to be messy over the next couple of days. Not only will this storm bring significant amounts of snow to parts of New Brunswick and Prince Edward Island, but there is expected to be several hours of freezing rain across Nova Scotia.

The storm will make its way into the region at around 9-10am on Thursday, with snow crossing eastward into New Brunswick from Maine and Quebec. The snow will quickly cross the province throughout the remainder of the morning, with the leading edge reaching PEI by 1-2pm.

By the early afternoon, more intense snowfall will begin to fall in New Brunswick. This heavy snow will persist for several hours across most of Central and Northern New Brunswick, at rates of 3-5cm/hr, which will rapidly result in over 30cm of snowfall accumulation by the end of the day.

Prince County, PEI can also expect some heavier snowfall beginning in the mid-afternoon and continuing into the evening, which will lead to overall accumulations of 15-30cm. The heavy snowfall will start to weaken during the evening, but light snow is expected to continue to fall overnight and through early Friday morning across Northern New Brunswick and into PEI.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 5PM AT Thursday

Snowfall totals decrease moving southward through New Brunswick and eastward across PEI because the forecast is a bit more complicated there, along with throughout Nova Scotia. Precipitation will reach the western shores of Nova Scotia at around 10-11am Thursday, not long after it starts in New Brunswick. The leading edge of the storm will see the precipitation start off as light snow as it crosses the province, but it will very quickly transition over to freezing rain, with a brief period of ice pellets in between.

This change in precipitations types will occur as a result of warm air aloft nudging its way into the region from the south. The warmer air will spread across a wide area and will lead to pronged freezing rain over much of Nova Scotia, with upwards of 5mm of ice accretion on untreated surfaces.

Precipitation Types with temperature profiles

The depth of the layer of warm air will play a critical role in precipitation type. As the warm air tries to push further northward, the layer will become shallower and this will lead to a slightly longer period of ice pellets (also called sleet) before it eventually switches over to freezing rain.

This will be the case in Northern Nova Scotia and into Cape Breton Island, as well as with most of PEI and Southern New Brunswick. In these areas, the ice pellets will add to the prior snowfall totals before there is a short-lived period of freezing rain and therefore less ice accretion overall.

Eventually, the warm air will reach the surface and temperatures will climb above freezing, starting in Western Nova Scotia at roughly 2-3pm. This will lead to the precipitation making a final transition from freezing rain to rain for a few hours as the storm continues to cross the region.

The precipitation across the region will taper off throughout Thursday evening. As previously mentioned, some light snow is expected to continue in Northern New Brunswick and PEI overnight, however, freezing rain is also expected to last in Cape Breton into the early morning hours of Friday as well.

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This storm is expected to bring some strong wind gusts to go alongside with the mixed bag of precipitation throughout the Maritimes. The gusts are expected to be the strongest across Nova Scotia, with gusts of 60-90km/h for the duration of the storm across the Mainland and over 100km/h in Northern Cape Breton. In New Brunswick and PEI, winds will be weaker, but gusts up to 60km/h are likely.

Luckily, the temperatures climbing after the freezing rain will help melt the ice buildup off of surfaces, especially from trees and power lines, ahead of stronger winds expected on Friday.

High Impact Winter Storm on the Way for Southern Ontario Starting Wednesday With Up to 40cm of Snow & Freezing Rain

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Confidence is growing that Southern Ontario is on track for what could be the most widespread and significant winter storm of the season so far. That said, there hasn’t been much competition in that regard, as most of this winter’s snowfall has come from localized snow squalls. However, a shift in the weather pattern has placed the region in an active storm track, and Mother Nature isn’t wasting any time delivering a disruptive winter storm right in the middle of the week.

Earlier, there was some uncertainty regarding the exact track of the system, which would have influenced snowfall amounts in different areas. However, in the past 24 hours, forecast models have begun to align on a more consistent storm track. Interestingly, the latest data supports what we initially projected, meaning there hasn’t been a major shift in the forecast.

Widespread snowfall accumulations of 20 to 40 cm are expected from Southwestern Ontario through Central Ontario and into the Ottawa Valley between Wednesday and Thursday. In the Golden Horseshoe and Deep Southwestern Ontario, precipitation will likely begin as snow, but there is potential for ice pellets, freezing rain, or even regular rain to mix in. This could limit snowfall totals, especially along the shorelines of Lake Ontario and Lake Erie, where temperatures may hover near the freezing mark.

For the Greater Toronto Area (GTA), the extent of mixing remains a key uncertainty. It could go either way. Right now, we’re forecasting 10 to 20 cm of snow, but if the mixing line stays south, snowfall amounts could surpass expectations, reaching 25 to 30 cm.

In Deep Southwestern Ontario, including Windsor, Chatham, and extending into the Niagara region, models suggest several hours of freezing rain Wednesday evening and overnight. Some localized areas could see ice accretion of 2 to 5 mm, leading to slippery, untreated surfaces and hazardous road conditions.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The storm is expected to arrive Wednesday afternoon, with scattered precipitation moving into Southwestern Ontario between 2 and 4 PM. While most areas will initially see snow, some models are aggressive in bringing freezing rain into Windsor and Chatham by late afternoon.

Before the main storm arrives, lake-effect snow may develop off Lake Ontario, affecting the Burlington and Hamilton corridor Wednesday morning into early afternoon. System snow should reach the GTA just before the evening rush hour, making for a difficult commute.

The latest model data has also increased wind projections, with gusts of 40 to 60 km/h in some areas. Combined with heavy snowfall, this could lead to blowing snow and reduced visibility. Non-essential travel should be avoided starting in the late afternoon, with conditions deteriorating further into the evening.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

By mid to late evening, snow will have spread across most of Southern Ontario, including Central and Eastern Ontario. A key feature to monitor will be the movement of the mixing line.

Current data shows a freezing rain corridor stretching from Leamington through Chatham and along the Lake Erie shoreline, with a narrow band of ice pellets from Windsor through just south of London and into Hamilton.

Meanwhile, heavy snow will persist across Sarnia, London, Kitchener, and the GTA. Snowfall rates will intensify after 9–10 PM, increasing from 1–2 cm per hour to 2–4 cm per hour. This will make it challenging for snowplows to keep up.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

After midnight, the mixing line may push north into parts of the GTA, bringing ice pellets and freezing rain to locations such as London, Burlington, Mississauga, and Toronto for several hours. However, this transition looks to be confined near the Lake Ontario shoreline, meaning snowfall will likely dominate farther inland.

Freezing rain will continue across Windsor and along the Lake Erie shoreline into the Niagara region, while heavy snow steadily blankets Central and Eastern Ontario overnight.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The system will begin its exit Thursday morning, with snow tapering off in Southwestern Ontario first. However, snow will continue across Central and Eastern Ontario.

In the Niagara region and along the Lake Ontario shoreline, mixing will remain a concern into the early morning hours. However, by 4–6 AM, colder air will push in, flipping precipitation back to snow. Any previously fallen precipitation may refreeze as temperatures drop, creating hazardous road conditions.

Expect treacherous travel conditions on Thursday morning. Roads will be slushy and icy in areas that saw mixing, while heavy snow will make roads impassable further north. Widespread school bus cancellations and school closures are likely.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Eastern Ontario will hold onto light to moderate snow through the late morning. However, models indicate some potential for mixing in the Kingston, Brockville, and Cornwall areas. This could result in light icing from freezing rain before a final transition back to snow.

Most of Southern Ontario will finally see an end to precipitation Thursday, aside from some lingering lake-effect snow near Lake Huron.

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Based on the latest data, the highest snowfall totals will likely be in Central and Eastern Ontario. A widespread 20–40 cm is forecast across Southwestern, Central, and Eastern Ontario. However, totals closer to 40 cm are most probable in Eastern Ontario, including Ottawa, where there’s even a slight chance of locally exceeding 40–50 cm.

Central and Southwestern Ontario, including Grey-Bruce, Kitchener, York Region, Simcoe County, Muskoka, and Peterborough, will likely receive 20–30 cm, with some areas near Lake Simcoe potentially exceeding 30 cm.

The exception will be the Lake Ontario shoreline and the International border, including Kingston, Brockville, and Cornwall. Lower snowfall ratios and a higher risk of mixing could keep totals below 20 cm. However, if mixing remains minimal, this area could exceed forecasts.

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The snowfall forecast becomes more uncertain in Deep Southwestern Ontario and the Golden Horseshoe, where multiple factors create a ‘boom or bust’ scenario. The GTA will start with heavy snow, likely reaching 10 cm fairly easily unless there’s a drastic shift in the storm track. The big question is how much more accumulates beyond that.

Some models suggest that if mixing does not occur, parts of the GTA could see 20–30 cm by Thursday morning. However, given the likelihood of overnight mixing, we expect totals to stay below 20 cm, which is why our official forecast remains at 10–20 cm.

London and Sarnia sit on the boundary between significant snow and mixed precipitation. The most probable outcome is 15–20 cm, though an overperformance remains possible.

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In Deep Southwestern Ontario and the Niagara region, snowfall amounts will be lower, with less than 10 cm expected. However, these areas will likely see prolonged freezing rain, with the heaviest ice accretion along the Lake Erie shoreline.

Models vary on how intense the freezing rain will be. Some project as much as 10 mm of ice accretion, but this seems unlikely given the presence of mixed precipitation and the relatively short duration of freezing rain. Our official forecast calls for 2–5 mm of ice accretion, though isolated pockets could see 7–10 mm if freezing rain persists longer than expected.

First Look: Major Winter Storm Set to Bring a Mixed Bag of Precipitation to the Maritimes

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Over the past few days, we’ve been monitoring the development of a major winter storm with the potential to have a significant impact in the Maritimes. In that time, the projected track of the storm has shifted back and forth, making it difficult to determine how exactly the storm would impact different parts of the region. Now that we’re less than 36 hours out, we’re starting to get a clearer picture of what can be expected from this storm.

The storm will begin early Thursday morning by bringing snow into the region from the west. Currently, it appears that the entirety of the Maritimes will see at least some snow, however precipitation won’t remain as snow for the entire storm for many in the region.

There is a high risk for prolonged freezing rain across parts of Nova Scotia, Prince Edward Island, and Southern New Brunswick as warm air is expected to flood northward throughout the day on Thursday. The freezing rain will eventually transition to rain in Nova Scotia, PEI and along the Fundy Coast in New Brunswick with the climbing temperatures, which may approach the double digits in Western Nova Scotia. The warm air should thankfully limit the impact of the freezing rain in many areas since a majority of the ice accretion should melt.

In Northern New Brunswick, on the other hand, the snow is expected to not only persist throughout the entire event, but will also be quite heavy. Early estimates are pointing at upwards of 40cm of snow here by the time the storm exits the region early Friday morning.

Exact timing, along with anticipated snowfall and freezing rain totals across the region, will be discussed in a full-length forecast that will be issued Wednesday evening so make sure to stay tuned for that.

Major Winter Storm on Track to Dump Up to 40cm of Snow Across Most of Southern Ontario Starting Wednesday

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Get your shovels ready, Southern Ontario! What many would consider our first true winter storm of the season is on the horizon. This moisture-laden system is set to arrive Wednesday afternoon, bringing heavy snowfall across a large portion of our region.

There’s still some uncertainty in the exact track, which will determine who sees the heaviest snow, but confidence is growing that much of Southern Ontario will experience significant impacts from this storm. Travel will likely become hazardous Wednesday evening into Thursday morning, and widespread school bus cancellations—and even full school closures—are almost certain on Thursday.

Based on the latest data, the heaviest snowfall is expected to stretch from Southwestern Ontario through Central Ontario and into the Ottawa Valley. Accumulations will likely range between 20 to 40 cm, with some localized pockets potentially exceeding 40 cm by the time the snow tapers off early Thursday afternoon.

The most challenging part of this forecast comes down to a narrow corridor from London through Hamilton, into the Greater Toronto Area (GTA), along the Lake Ontario shoreline, and into extreme Eastern Ontario along the international border. These areas are likely to start off with snow, but depending on the storm’s track, a transition to ice pellets, freezing rain, or even regular rain could occur during the evening and overnight.

The exact snowfall amounts in this corridor remain highly uncertain, as even a fraction of a degree difference in temperature could mean the difference between 5 cm and 30 cm of snow.

The risk of freezing rain also appears significant for areas in deep Southwestern Ontario, including Windsor, Chatham, and communities along the Lake Erie shoreline, where several hours of ice accretion could result in hazardous road conditions and localized power outages.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The storm will begin impacting Southern Ontario on Wednesday afternoon, with the initial bands of snow spreading into deep Southwestern Ontario, including Windsor, Sarnia, Chatham, and London. By the mid-to-late afternoon, snow will have moved into Hamilton, Niagara, and the Greater Toronto Area, just in time for the evening commute.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

Steady snowfall will continue through the dinner hour, with snowfall rates gradually increasing as the system spreads further across the region. Central and Eastern Ontario will see snow begin around the dinner hour into the early evening, while the Ottawa Valley may not see the first flakes until mid-to-late evening.

Snow will continue throughout the night across much of the region, with varying intensity. Unlike some past storms, this event isn’t expected to bring extreme snowfall rates, with accumulations of around 2 to 4 cm per hour at most. However, the prolonged nature of this storm, lasting 12 to 16 hours in many areas, will allow totals to build up significantly.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Another key factor in determining final snowfall amounts will be how far north the mixing line extends into Southern Ontario. Earlier model runs suggested a more northern track, which would allow warmer air to push into areas along the Lake Erie and Lake Ontario shorelines, leading to a transition from snow to ice pellets, freezing rain, or rain.

However, more recent model data from Monday evening has trended slightly further south, reducing the risk of mixing for some areas. That said, some models, including the American (NAM) and European models, still show a more northern mixing line, which could bring ice and rain into parts of deep Southwestern Ontario, London, and Hamilton.

If this occurs, Windsor and areas along the Lake Erie shoreline could see several hours of freezing rain, resulting in ice buildup on untreated surfaces, power lines, and roads.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

On the other hand, the Canadian (RGEM) model, along with the higher-resolution American NAM 3km model, suggest a more southern storm track, which would keep most of Southern Ontario in the snow zone.

If this scenario plays out, snowfall accumulations could be much higher in places like London, Hamilton, and the Golden Horseshoe, with totals ranging from 20 to 30 cm and minimal mixing.

Some models also indicate the possibility of mixing slightly north of Lake Ontario and along the St. Lawrence River, including Kingston, Brockville, and Cornwall, which could lower snow totals in these areas. However, the latest data suggests this region may stay entirely on the snowy side of the system.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

As the storm progresses overnight, those areas that remain on the snow side will continue to see accumulation through early Thursday morning. Snowfall rates could briefly reach 2 to 4 cm per hour in heavier bands but will likely average closer to 1 to 2 cm per hour.

Fortunately, winds won’t be particularly strong, with gusts expected to range from 20 to 40 km/h at most. While some blowing snow is possible, full-blown blizzard conditions are not expected with this storm.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By mid-morning Thursday, high-resolution models suggest a final burst of heavier snow around the Golden Horseshoe, Lake Simcoe, and Eastern Ontario. Snowfall rates could briefly spike to 4 to 6 cm per hour as the back end of the system moves through during the morning rush hour.

Travel conditions will likely be very poor on Thursday morning, and all non-essential travel should be avoided. Widespread school bus cancellations are almost a certainty given these conditions.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

A rapid improvement is expected in Southwestern Ontario by late morning, with snowfall tapering off to light flurries. However, it will take time for road crews to clear the heavy snowfall, so road conditions may remain hazardous into the early afternoon.

For Central and Eastern Ontario, snow will linger into the early afternoon before finally winding down around midday for the GTA and Central Ontario and mid-afternoon for the Ottawa Valley.

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By the time the storm wraps up, a broad region across Southern Ontario, including the Lake Huron shoreline, Sarnia, Kitchener, Barrie, Muskoka, Peterborough, and the Ottawa Valley, will likely see between 20 and 40 cm of fresh snow. Mixing is unlikely to be a factor in these areas, though there’s always a slight chance of a last-minute shift in the storm track.

The biggest uncertainty lies within a narrow corridor that includes London, Woodstock, Hamilton, Mississauga, Toronto, Belleville, Kingston, Brockville, and Cornwall. This area will likely begin with snow on Wednesday but could see ice pellets, freezing rain, or rain mix in during the late evening and overnight hours, which would reduce total snowfall amounts.

A conservative estimate for this region is at least 10 cm of snow, though some areas, particularly along the northern edge of this zone, could see totals closer to 20 to 30 cm. The current model trends lean toward a slightly more southern storm track, but we are waiting to see if this pattern holds before making final adjustments to the snowfall forecast.

For Windsor, Chatham, and areas along the Lake Erie shoreline, including Niagara, a mix of snow and freezing rain is expected. Some locations could experience several hours of freezing rain, leading to ice accretion of 4 to 8 mm, which may cause localized power outages. However, if the mixing line remains further south, these areas could still end up seeing significant snowfall, possibly exceeding 20 cm.

The bottom line is that while we have high confidence in a significant winter storm, the local impacts will ultimately depend on the storm’s exact track, which may not become fully clear until just before the system moves in.

A more detailed forecast with refined snowfall and freezing rain estimates will be released late Tuesday as newer model data becomes available.

Snowy System Brings Double Digit Snowfall Accumulation to Greater Toronto Area & Southwestern Ontario This Weekend

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While many parts of Southern Ontario have been hit hard by snow squalls this winter, others have barely seen any accumulation.

The snowbelt regions east of Lake Huron and Georgian Bay have faced relentless lake-effect snow, while areas like Deep Southwestern Ontario, the Golden Horseshoe, and Southeastern Ontario have largely remained outside the squall zones.

The reason? This winter has been dominated by localized snow squalls rather than widespread storms. The extreme cold throughout January kept the storm track well south of the Great Lakes, shielding much of the region from major systems.

Aside from the occasional Alberta Clipper, it’s been relatively quiet. But that’s about to change as we shift into a more active storm track that places Southern Ontario directly in its path.

A moderately strong snowy system is on track to bring steady, accumulating snowfall across a wider area, including the GTA—one of the least snowy regions so far this season. Snow is expected to begin Saturday afternoon, with the heaviest accumulation occurring Saturday evening.

In fact, this system could bring Toronto its largest one-day snowfall of the season. The city’s current highest daily total sits at just 6.6 cm, recorded in early December. But with this storm, a widespread 10-15 cm of snow is looking increasingly likely, with some areas west of Lake Ontario possibly approaching 20 cm due to lake enhancement.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The first snow bands will push into Southern Ontario from the west by mid-afternoon Saturday, with flurries likely developing east of Lake Huron between 2-4 PM before spreading into the GTA around the dinner hour.

At first, the snowfall will be light, but intensity will gradually increase through the late afternoon and early evening as stronger snow bands move in. Windsor and Chatham could see some mixed precipitation, with a chance of freezing rain or drizzle before switching over to snow.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

By early evening, snowfall will expand across most of Southern Ontario, bringing steady accumulation.

The heaviest snow is expected west of Lake Ontario, stretching into Kitchener and Goderich, where snowfall rates could reach 1-2 cm per hour.

ESTIMATED WIND GUST - MAP FROM WEATHERBELL

Winds gusting 40-50 km/h along the Lake Erie shoreline Saturday evening may not be extreme, but they could still create minor blowing snow when combined with the steady snowfall, making travel conditions tricky.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

Snow will continue falling through the evening, gradually spreading toward Eastern Ontario. While Ottawa might see some light snow, accumulation should remain minimal.

The heaviest snow in Eastern Ontario will focus along the Lake Ontario shoreline, including Belleville and Kingston.

As we approach midnight, snow will begin tapering off from west to east, with Lake Huron regions clearing out first. For the GTA, heavier snow may persist a few hours past midnight before gradually weakening.

By early Sunday morning, the system will have moved out of most of Southern Ontario, with only lingering light snow possible in Eastern Ontario.

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Recent model trends suggest a stronger system than initially expected, though there remains some uncertainty. Forecasts have bounced between 5-10 cm and 15-25 cm in different model runs.

The current consensus suggests a general 10-15 cm corridor extending from Lake Huron through Kitchener, the Golden Horseshoe, and into the Kingston area, with localized pockets nearing 20 cm.

For areas further north, including Simcoe County, Kawartha Lakes, and Brockville, as well as Sarnia and London, 5-10 cm of snow is expected.

The least snowfall will be in the Ottawa Valley, where less than 5 cm is likely. Deep Southwestern Ontario, including Windsor and Chatham, will see the lowest totals, with 2-5 cm possible, along with the risk of freezing rain.

This will be one of the most widespread snowfalls of the season, especially for regions that have barely seen measurable snow this winter. Stay tuned for further updates as the system approaches.

Snow Squalls to End Off the Week in Parts of Southern Ontario With Up to 25cm of Snow Possible by Friday

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While we’ve had a break from snow squall activity over the past week, they are expected to return as we close out the week, bringing another round of lake-effect snow to areas around Lake Huron and Georgian Bay.

As the system that brought a messy mix of wintry weather moves out, colder air will briefly settle into Southern Ontario. This drop in temperature, combined with strong westerly to northwesterly winds blowing over the still mostly ice-free lakes, will create the perfect conditions for snow squall development.

Overnight Thursday, shifting winds will likely trigger several narrow bands of heavy snow that will sweep across Southern Ontario before becoming more organized over Lake Huron and Georgian Bay.

While these bands won’t last long—most areas will only see snow for 15 to 30 minutes—they could still create hazardous driving conditions. Strong wind gusts of 70-80 km/h will cause blowing snow, significantly reducing visibility on the roads.

However, for regions within the snowbelt, which have already been hit hard by squalls in recent weeks, this could be another significant snowfall event. Parts of Grey-Bruce and Simcoe County may see totals reaching 15 to 25 cm in the hardest-hit communities by the end of Friday.

HOURLY SNOWFALL RATE/intensity - MAP FROM WEATHERBELL

More organized squalls are likely to develop early Friday morning, targeting the Bruce Peninsula and extending into Simcoe County. This narrow but intense band will likely persist throughout much of the day, though it may shift somewhat as winds fluctuate.

Current model data indicates that the heaviest snow will remain focused within the Wiarton-to-Owen Sound corridor in Grey-Bruce and between Orillia and Barrie in Simcoe County. At times, the squall could extend further inland, bringing periods of heavy snow to parts of Kawartha Lakes, Durham, and Peterborough during the morning and afternoon.

By Friday evening, a shift in wind direction will bring a few hours of intense snowfall to parts of Southern Muskoka, including MacTier, Port Carling, Bala, Gravenhurst, and Bracebridge. However, this squall is expected to weaken quickly after midnight as winds subside.

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With the snow band moving around throughout the day, widespread extreme accumulations are less likely, but it will allow more regions to see bursts of heavy snowfall at different times.

We’re expecting total snowfall accumulations of 15 to 25 cm across the central Bruce Peninsula, including Wiarton and Lion’s Head, extending into most of Simcoe County.

The City of Barrie is expected to avoid the worst of the snowfall, but if the squall sinks slightly farther south for a few hours, the city could still see around 10-15 cm of accumulation.

For the rest of Grey-Bruce, including Owen Sound, Hanover, and Collingwood, as well as Muskoka, Kawartha Lakes, and Peterborough, snowfall totals will generally range between 5 to 10 cm, though some localized pockets may receive up to 15 cm.

Outside of the snowbelt, snowfall will be minimal, with 2-5 cm expected across the rest of Central Ontario and less than 2 cm for Eastern Ontario and the Golden Horseshoe.

Deep Southwestern Ontario will likely remain snow-free from this round of lake-effect snow.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

After the snow squalls, attention will turn to Saturday night, which, at one point, looked like it could bring Southern Ontario its strongest winter storm of the season. However, recent model data now suggests that much of the system’s moisture may stay south of the border, shifting into the U.S. Northeast instead.

If this trend continues, instead of widespread snowfall totals of 10-20 cm, most of Southern Ontario could see just 5 to 10 cm—and even that might be on the high end.

For those hoping for a big winter storm, it looks like luck isn’t on your side this time. That said, we’re still in an active storm track, and the next few weeks will bring more chances for Southern Ontario to get hit with a classic winter storm.

Incoming Storm's Shift Expected to Keep Heaviest Snow Out of the Maritimes, Widespread 5-10cm By Friday Afternoon

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For the past several days, we’ve been tracking the development of a winter storm, with a considerable freezing rain component, set to impact the Maritimes later in the week.

Thankfully, the projected track of the storm has taken a southward shift, ahead of the storm’s development Wednesday afternoon. This will keep the heaviest precipitation from the storm, expected to fall mostly as snow, away from the Maritimes as it approaches the region on Thursday.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 3PM AT Thursday

The leading edge of the snow will arrive in Western Nova Scotia and Southwest New Brunswick in the mid-afternoon Thursday, shortly after 3pm. It will cross the region fairly quickly, reaching Prince Edward Island in the evening, around 7-8pm and Cape Breton Island by 9pm.

Some heavier snow is anticipated to move into Western Nova Scotia in the early evening and this area can expect to be on the top end of the 5-10cm range, with local amounts even exceeding 10cm.

While this snowfall is crossing the Maritimes, warm air will surge northward into Nova Scotia. This will bring temperatures above freezing and result in a transition from snow to rain in Western Nova Scotia around 9pm, with a brief period of freezing rain or ice pellets in between. The temperature will also rise along the Fundy Coast of New Brunswick, but whether or not the transition to rain occurs here is questionable.

Some weather models show more of this freezing precipitation falling than others, but regardless, it shouldn’t amount to much. Temperatures are expected to climb above freezing with the transition to rain, melting any ice buildup that might occur.

Model Image showing the location and intensity of snow (Blue), Rain (Green), Freezing rain (Pink), and Ice pellets (Orange) at 8PM AT Thursday. Note: this particular model does not cover the entire maritimes.

As the system pushes northeastward across the Maritimes, the snow-to-rain transition will also cross Nova Scotia. The rain won’t last long, though, as the precipitation will start to exit the region beginning around 9-11pm.

All precipitation is expended to be finished by around sunrise on Friday, after a widespread 5-10cm of snow falls across most of the region. Lesser amounts will be measurable in Nova Scotia following the increase in temperatures and the rain melting what had previously fallen.

Strong winds aren’t expected to be much of a concern with this system. The winds will pick up Thursday evening, leading to gusts of up to 70km/h across Nova Scotia, PEI and Southern New Brunswick overnight and into Friday morning. The western edge of the Cape Breton Highlands, however, could see gusts in excess of 100km/h for a few hours Friday morning before dying down ahead of sunrise.

Looking ahead, we have our eye on another storm that could impact the Maritimes on Sunday and we will have more details on that in the coming days.

Wintry Mix of Snow, Sleet and Freezing Rain Threatens Thursday Morning Commute Across Southern Ontario

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A shift in the weather pattern across Southern Ontario over the past few days has brought a noticeable retreat from the extreme cold, with temperatures returning to near-seasonal values. However, this shift has also placed the region on a more active storm track, a pattern we first experienced with Monday’s messy system.

The next round of unsettled weather was initially showing signs of a prolonged freezing rain event on Thursday. However, recent model trends indicate a significantly weaker system than previously expected. While this storm will still impact Southern Ontario, the main threat now appears to be light freezing rain and snow, particularly during the Thursday morning commute.

Although snowfall totals won’t be overly impressive, Central and Eastern Ontario could see an average accumulation of 4 to 8 cm by the end of the day. The primary concern will be the mix of precipitation types, which could create slushy and icy road conditions, making for a slick and potentially hazardous commute.

Looking ahead to the weekend, we are closely watching a moisture-laden system that could bring Southern Ontario its first true widespread snowstorm of the season. This storm has the potential to impact even those regions that have largely avoided significant snowfall so far, including Deep Southwestern Ontario and the Golden Horseshoe.

Current projections suggest snowfall totals could range from 10 to 25 cm, though these estimates will likely be refined as we get closer to the event.

PRECIPITATION TYPE OVER LAST 6 HOURS - MAP FROM WEATHERBELL

Thursday’s system is expected to begin during the morning hours as light precipitation moves in from the southwest. High-resolution models, such as the American model shown above, suggest that the precipitation will be quite scattered with dry pockets throughout. However, if the precipitation takes the form of light flurries or drizzle, some models may be underestimating its extent.

For Central and Eastern Ontario, precipitation will likely fall as snow. Across the Golden Horseshoe, it may also start as snow during the mid-morning hours before transitioning. Meanwhile, areas along the Lake Erie shoreline and Deep Southwestern Ontario will be more prone to freezing rain and ice pellets from the onset.

Travel conditions could become challenging, particularly in the morning as freezing rain coincides with rush hour across Southwestern Ontario and into the Golden Horseshoe.

At this point, it’s uncertain whether this system will be strong enough to prompt widespread school bus cancellations. However, the highest risk for disruptions will be in Windsor, Chatham, and London, where precipitation is expected to begin earlier in the morning with a higher likelihood of freezing rain.

PRECIPITATION TYPE OVER LAST 6 HOURS - MAP FROM WEATHERBELL

By early afternoon, precipitation should become more widespread, particularly in Central and Eastern Ontario, as drier areas fill in with moisture. Despite this, snowfall rates are expected to remain manageable, likely staying under 1 cm per hour. However, snow could persist for a solid 6 to 8 hours through the late morning and afternoon, leading to gradual accumulation.

Meanwhile, the freezing rain threat will begin expanding toward Hamilton and the western GTA, with ice pellets potentially mixing in as the transition from snow to freezing rain occurs.

Gradually, precipitation will taper off in Deep Southwestern Ontario, with lingering drizzle as temperatures slowly rise above freezing. This slight warm-up will help melt any ice accretion from earlier in the day.

Across the rest of Southern Ontario, precipitation should wind down by late afternoon or early evening. In the wake of the system, some minor lake-effect snow may develop around Georgian Bay and Lake Huron, but we are not expecting any organized lake-effect activity at this time.

PRECIPITATION TYPE OVER LAST 6 HOURS - MAP FROM WEATHERBELL

While Thursday’s system may be relatively minor, it could serve as a precursor to a much more impactful storm set to arrive this weekend.

Uncertainties remain, and details could shift as we get closer to Saturday. However, all major weather models continue to signal a strong system targeting Southern Ontario late Saturday into Sunday.

The exact track and intensity will determine which areas see the most significant impacts. At this point, current projections suggest a prolonged freezing rain threat for Deep Southwestern Ontario and areas along the Lake Erie shoreline. Meanwhile, heavy snow, with potential accumulations between 10 and 25 cm, could affect parts of the Golden Horseshoe, Central Ontario, and Eastern Ontario.

Again, this forecast is subject to change, but this storm has the potential to be a high-impact event for much of Southern Ontario. Stay tuned, as we’ll be providing more detailed updates in the coming days!