Ontario's August forecast for 2026 has officially arrived and here's what to expect

Summer in Ontario has been all over the place so far, with plenty of precipitation and a major heat wave that has consistently pushed humidex values into the mid-40s, and that variability is expected to continue throughout the season, according to a new long-range forecast. 

The Old Farmer's Almanac released its August forecast for southern Ontario on Wednesday, providing an early look at how the second half of the summer season will unfold. 

The forecast breaks down the upcoming month into several multi-day blocks, and rather than providing specific temperature forecasts, predictions any periods of heavy precipitation and general trends. 

The period of Aug. 1 to 9, which includes the August Civic Holiday long weekend, is expected to bring some thunderstorms, along with warm temperatures. Between Aug. 10 and 16, sunny skies are expected, with cool temperatures in the east and warm conditions in the west. 

More isolated thunderstorms are expected through Aug. 17 to 21, but warm temperatures will likely stay put. According to the forecast, the rest of August will likely play out the same way, with more thunderstorms and warm temperatures between Aug. 22 and 26. 

From Aug. 27 to 31, even more thunderstorms are expected in the east, while southwestern Ontario is expected to see sunny skies and cool temperatures. Overall, the average temperature in August is predicted to be 20 degrees C, which is 1 C below average in the east and 1 C above average in the west. 

Precipitation totals will likely hit the 125 mm mark ( which is 70 mm above average in the east, and 20 mm above in the west). 

However, before we jump ahead to August, the Old Farmer's Almanac previously released its July forecast, and so far, its predictions for the week of July 1 to 7 (hot temperatures, thunderstorms, and sunny skies) have been mostly accurate.

Between July 8 and 12, more isolated thunderstorms are expected, along with warm temperatures. Throughout mid-July, we can expect even more thunderstorms, but pleasant temperatures will stay put, according to the forecast. 

Southern Ontario is expected to close out July with, you guessed it, even more thunderstorms. Overall, the average temperature in July is expected to be 21 C, which is 1 C below average in the east, and 1 C above average in the west. Total precipitation amounts are expected to hit 95 mm (which is 70 mm above average in the east and 40 mm below in the west). 

Another forecast released this week also predicts that much of southern Ontario is in for above-average warmth this summer. According to the three-month probabilistic forecasts released by Environment and Climate Change Canada (ECCC), the majority of southern Ontario, including the GTA, is looking at a 70 to 80 per cent chance of above-average warmth between July and September 2026.