If you’ve been craving long, sunny days and warmer weather, this summer may finally deliver.
According to The Weather Network’s recently released summer forecast, much of Canada can expect above-normal temperatures during the months of June, July, and August—with Ontario heading into a warm, humid season that could kick off with a heat wave.
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
A warm summer from coast to coast
Across the country, temperatures are forecast to climb above seasonal norms, particularly through July and August. The most intense heat is expected from the Rockies through to northwestern Ontario, where extended heat waves and episodes of extreme heat are likely. While British Columbia could see some of that warmth at times, forecasters don’t expect it to persist in the west.
In Eastern Canada, including Ontario, Quebec, and Atlantic Canada, the summer outlook leans toward warm and humid, but without the same level of extreme or sustained heat. Daytime highs should hover near or slightly above normal, while the muggy conditions will likely keep overnight temperatures warmer than usual.
On the precipitation front, most of Western Canada is expected to see below-normal rainfall, raising concerns about drought, especially across the southern Prairies.
Meanwhile, thunderstorms may become a common feature around the northern edge of the heat dome developing over the central U.S.—a pattern often called the “ring of fire.” These storms could bring bursts of torrential rain and localized flooding, but are unlikely to offset wildfire risks in parts of B.C. and northwestern Ontario.
What Ontario can expect
Northern Ontario
Western areas like Thunder Bay are in for a hot and dry summer, with daytime highs consistently above normal. In contrast, eastern areas such as Sudbury will experience warmer temperatures as well, but with added humidity. This will bring an increased chance of showers and thunderstorms, particularly at night. The wildfire risk remains a concern across much of northern Ontario, especially west and north of Lake Superior. If that risk is realized, the resulting smoke could affect air quality in other parts of the province and even beyond.
Southern and eastern Ontario
After a drawn-out and unpredictable spring, southern and eastern Ontario—including London, Toronto, and Ottawa—can expect a swift switch to summer weather in early June. Forecasters say the first heat wave could arrive before Canada Day.
Though it will be warm and muggy, the region isn’t expected to endure long periods of extreme heat. Cool fronts should occasionally bring relief, helping to balance out the summer pattern. That said, overnight temperatures may stay noticeably high, thanks to the persistent humidity.
Precipitation levels are expected to be near or slightly above normal, with occasional dry spells but no significant drought. The humid air will also bring an increased risk of strong thunderstorms and heavy rain.
Summer plans? Pack the sunscreen—and maybe an umbrella
Overall, Ontarians can look forward to a summer that feels more seasonal than springs past. Expect warm, humid days with breaks of cooler air, and keep an eye out for those classic pop-up summer storms.
Whether you're heading north to the lakes or sticking closer to home, summer 2025 is shaping up to be a true mix of heat and humidity, with just enough rain to keep your garden happy.
