A look into Ontario’s September forecast for 2026

With the official halfway point of summer rapidly approaching, you might already be dreaming of the days you can switch out your shorts for cozy sweaters and your lemonade for pumpkin spice lattes.

If you’re actually excited for the cooler weather, you’ll be pleased to hear that a new long-range forecast released this week offers an early look at what we can expect as we transition into fall next month.

The Old Farmer’s Almanac dropped its September 2026 long-range weather forecast for southern Ontario, which breaks up the month into several multi-day periods to predict weather patterns and temperature trends.

Between Sept. 1 and 4, southeastern Ontario is expected to see cool temperatures along with sunny skies, while the west might experience some precipitation.

From Sept. 5 to 8, warm temperatures might be interrupted by thunderstorms across the province. The following week is expected to bring cool temperatures across the province, along with showers in the east and sunny skies in the west.

The week of Sept. 17 to 23 is expected to be all over the place, with showers, followed by sunny skies and cool temperatures. The month is expected to close out on a classic fall note, with rainy and chilly conditions between Sept. 24 and 30.

Overall, the average temperature next month is anticipated to be 15 degrees C, which is 1 C below average. Precipitation levels are expected to be on the higher side at 115 mm, which is 25 mm above average.

If you’re not ready to embrace fall just yet, the good news is that we still have several weeks of summer and warm temperatures to get through before the season changes.

According to the Almanac’s August long-range forecast for southern Ontario, more sunny conditions are expected from Aug. 10 to 16, followed by warm temperatures and isolated thunderstorms between Aug. 17 and 21.

From Aug. 22 to 31, we can expect more thunderstorms and warm conditions to close out the month, although there will be a bit of temperature variability depending on where you reside.

The average temperature in August is expected to be 20 C, which is 1 C below average in southeastern Ontario and 1 C above average in the west. Precipitation totals are expected to reach 125 mm, which is a staggering 70 mm above average in the east and 20 mm above average in southwestern Ontario.

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