Ontario's summer forecast for 2025 has arrived and here's what you can expect

If you've been crossing your fingers for a hotter-than-usual summer after a drawn-out winter and an unpredictable spring in Ontario, you're in luck. 

According to The Weather Network's 2025 summer forecast, much of Canada is gearing up for a sunny season that will be warmer than normal.

And Ontario is no exception. 

Get ready to soak up the sun, Canada! ☀️ After a tough winter and unpredictable spring, The Weather Network predicts a warmer-than-normal summer across most of the country. Get all the details in your #SummerForecast https://t.co/YfSuM8dv0p

— The Weather Network (@weathernetwork) May 28, 2025

From June through August, the majority of Canada is expected to bask in above-average temperatures. For Ontario, the warmth will come with a mix of weather patterns, depending on where you are in the province. 

In southern and eastern Ontario, including cities like London, Toronto, and Ottawa, a warm and humid summer is on the horizon. Early June is forecast to usher in a swift transition to higher temperatures, and we might even experience our first heat wave before Canada Day. 

Despite this, the forecast indicates that a cool front will also bring periods of more refreshing weather, amid possible heat waves. Daytime highs are expected to be near normal or slightly above normal, but nighttime temperatures will likely stay elevated due to high humidity. 

The bad news is that the muggy atmosphere will also fuel more frequent showers and increase the risk of thunderstorms, with precipitation totals for the summer expected to be near or above normal. 

Still, we should still experience stretches of drier weather through the summer, and The Weather Network does not expect widespread or prolonged drought in this region. 

The forecast for northern Ontario is a little more complicated. Western parts of the region, particularly west of Lake Superior and cities like Thunder Bay, can expect a hot and dry summer. Areas to the east of Lake Superior, including Sudbury, will see warmer-than-normal temperatures, but with higher humidity. 

This is expected to lead to increased chances of showers, thunderstorms, and muggy nights, although daytime highs might not reach the extremes seen farther west. One of the most pressing concerns for northern Ontario is the heightened threat of wildfires, especially north and west of Lake Superior. 

"If this threat is realized, the fires could have a far-reaching impact on the other parts of the country with smoke and a risk for poor air quality at times," the network notes.

Wildfires did indeed affect air quality in 2023, when heavy smoke filled the air in urban centres like Toronto for weeks that summer.

Outside the province, the Atlantic hurricane season is expected to be near normal or slightly more active than usual. Interestingly, that means that the upcoming season should have fewer tropical storms and hurricanes than other seasons in the past decade. 

However, the anticipated jet stream pattern could bring an elevated risk for a tropical system to track into the northeastern U.S., which would also impact eastern Ontario.