Southern Ontario: Fall Weather Hazards Outlook for Friday, October 29, 2021

Forecast Discussion

Heavy rain will start to move into regions along the Lake Erie shoreline early Friday and continue throughout the day. Other parts of Southern Ontario including areas around GTA and into Eastern Ontario will also see some rain later in the day and into Saturday morning, but it’s not expected to be as intense. Rainfall totals between 20-40mm are expected from the Hamilton/Niagara region to Extreme Southwestern Ontario (Windsor, Chatham etc.).

The bulk of the rain will fall on Friday but around 5-10mm may come overnight into Saturday morning with higher amounts on Saturday for Eastern Ontario. Rainfall totals between Friday and Saturday may exceed 25mm around the GTA and the Lake Ontario shoreline although 25+mm isn’t expected on one day so that’s not included on the map. Other areas can expect 5-10mm with lower amounts the further north and west you go.

In addition to the rainfall, there is the risk of frost for parts of Eastern Ontario on Friday morning. Temperatures are expected to come near the freezing mark which may allow for some frost to develop particularly in higher elevations around Bancroft and Algonquin Park.