Southern Ontario under a hoodie while Moosonee basks in shorts this week
Hudson Bay will likely be hotter than a backyard barbecue in the Greater Toronto Area (GTA) for the week ahead as southern Ontario's temperatures will fizzle by comparison
The warmer weather is finally making its way eastwards across the country this week, giving parts of Eastern Canada a chance to see some summer-like heat.
The good news is that some Ontario communities will likely join Canada's 2025 30-degree club this week. It is good news, if you live in northern Ontario, that is. That type of heat will take a little longer to hit southern Ontario as folks in the region will more likely opt for the hoodies, rather than donning summer shorts this week.
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Temperatures may hit 30°C for parts of northern Ontario this week, including Moosonee, Pickle Lake, Kenora, Dryden and the Sioux Lookout, especially on Tuesday.
Summer-like heat hits parts of Ontario
By Tuesday, the early tease of summer-like heat will spread into northern Ontario.
A ridge of high pressure is set to push directly over Ontario, so the forecast should be straightforward. Think again, the stubborn lake breezes and moisture sneaking under the ridge across the south will seriously dampen temperatures on Tuesday.
A warm front lifts past Hudson Bay on Tuesday, ushering in numerous 30-degree readings across northwestern Ontario––highly anomalous for mid-May.
Some communities that could see 30°C+ temperatures:
Moosonee
Pickle Lake
Kenora
Dryden
Sioux Lookout
While temperatures in the north will be more than 20°C above normal for this time of year, temperatures are likely to fall several degrees below seasonal along the western end of Lake Ontario as an east wind provides some unwelcome air conditioning. Burlington, Ont., will see just a high of 13°C on Tuesday.
On Tuesday, shower threats increase in southwestern Ontario, pushing northward through the afternoon. For those in the south looking for warmer days, the lake breeze is weaker on Monday, so a short trip inland means you’ll be rewarded with temperatures in the low- to mid-20s.
Is it any better on Wednesday? Not really, the same upper trough that’s south of the Great Lakes will bring ample cloud cover and spotty shower chances, while a sliver of northern Ontario bakes in the heat once again.
By Friday, the Lake Ontario breeze will slacken a bit, signalling a trend for temperatures to bounce back closer to seasonal.
On that note, we should head into the long weekend with warm temperatures. However, it looks like we will have an increasing risk for a period of unsettled, wet weather at some point during the weekend, followed by cooler temperatures.
A period of cooler weather is expected for the week after the long weekend and the final weekend of May.