Tire swap time: Snowy taste of winter is coming to southern Ontario
A perfect pattern is setting up to bring cold air and snow to southern Ontario by the end of the week. See which areas will be most affected by lake-effect snow and the season's coldest temperatures.
While other provinces have had a snowy taste of the winter to come, temperatures in Ontario have stayed well above seasonal thanks to a block of high pressure off the United States' East Coast.
But that is about to change. A deep, upper-level trough is forecast to dig across much of Eastern Canada and the U.S. by the end of the week, dragging cold, northern air southward.
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That means some areas are in line to see some of their snowfall of the season. While accumulations may not be high, the first snowfall can catch many drivers off guard, especially for those who haven't put their winter tires on.
Potential for first flakes by Friday
This is expected to be the coldest burst of air of the season so far for southern Ontario, with temperatures forecast to fall Thursday into Friday.
Daytime highs across the region on Friday are forecast to stay in the single digits, and wind chills should make it feel even colder.
Toronto's best chance to see the thermometer dip to freezing could be Thursday or Friday night.
Forecasters are also closely watching for a low-pressure system to form over Illinois by the midweek, most likely staying south of the border as it tracks over Lake Erie. But, its close pass may trigger showers across southern and eastern Ontario Thursday into Friday.
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Cold air being pulled behind the developing low could help to develop flurries just south of the Great Lakes.
Areas to watch will be Sarnia and the snowbelt communities for the first accumulation of the season. However, Sarnia and surrounding cities should see some rain mixed in with the snow from Thursday night through Saturday morning, which would reduce snow totals.
Lambton County could see 10-15 cm of snowfall through Saturday, although a transition over to rain later in the day means we won't see 10-15 cm of snow actually accumulate.
The snowblet off Georgian Bay's southern shore is also in store for some snowfall, with the heaviest-hit areas forecast to see 10-15 cm.
Some flurries may also make it into the GTA, which would make Toronto see both its first snowflakes and zero-degree reading of the seaon on the same day.
Stay with The Weather Network for more information and updates on your forecast across Ontario.