Ontario’s three-month weather forecast is out and here’s what to expect

With just a few weeks of summer left, the countdown to sweater weather is officially on — but if you’re not quite ready to trade in your T-shirts for cozy sweaters, there’s some good news on the horizon for you.

Environment and Climate Change Canada (ECCC) released its three-month probabilistic forecast on Monday, offering an early look at the temperature trends we can expect between September and November 2026.

Every month, the federal department uses its prediction system to forecast “the evolution of meteorological trends over the next seasons,” but does not highlight major weather-related events, such as storms or periods with heavy precipitation.

According to the models, southern Ontario, including the GTA, is looking at a 40 to 50 per cent chance of recording above-normal temperatures during this three-month period.

Based on the department’s map, the further north you get in the province, the higher the chance of seeing above-normal temperatures this fall. Large swaths of the province have between a 50 and 70 per cent chance of recording hotter-than-usual temperatures, while areas just off Hudson Bay have an 80 to 90 per cent chance.

The second model outlines the probability of experiencing near-normal temperatures this upcoming fall. Here in southern Ontario, we’re looking at a 30 to 40 per cent chance of temperatures being in line with what’s typically seen during this period.

The last map shows the probability of below-normal temperatures. While most of southern Ontario has a 10 to 20 per cent chance of chillier-than-normal temperatures, some areas near Ottawa and Lake Erie have a slightly elevated chance, between 20 and 30 per cent.

Although this forecast suggests Ontario’s fall might be warmer than usual, other prediction systems, including the Old Farmers’ Almanac, aren’t so confident. In its fall forecast released last month, the Old Farmers’ Almanac predicts that September will be cooler-than-normal in southern Ontario before temperatures rebound and return close to normal in October.

According to its long-range forecast for the region, the average temperature in September is expected to be 15°C, just 1°C below average.

The forecast also warned that most of Canada could receive above-average precipitation this fall, including in southeastern Ontario, where rainfall will be “well above average,” and southwestern Ontario, which will likely see “slightly above average” rainfall.

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