What the next three months of spring and summer weather will look like in Ontario

Although May has kicked off on a rather chilly note compared to previous years, there will be no shortage of blazing hot days in Ontario over the next few months.

Environment and Climate Change Canada (ECCC) releases its three-month temperature and precipitation probabilistic forecasts at the end of each month, and its latest outlook covers the period between May and July 2026, offering an early look at how end-of-spring and summer temperatures could play out this year. 

Still, it's important to note that the prediction system aims to "forecast the evolution of meteorological trend over the next seasons," and does not identify periods of heavy precipitation or any notable weather-related events, such as storms. 

The forecast models suggest that temperatures will vary across Canada over the next three months, with most regions, including southern Ontario, more likely to see above-average warmth. 

According to ECCC's first map, most of southern Ontario, including the GTA, has a 40 to 60 per cent chance of seeing above-normal temperatures during the period between May and July. Northeastern parts of the province are looking at a 40 to 50 per cent chance of above-normal temperatures, while the northwest has a slightly elevated, 60 to 70 per cent chance. 

In another map, models predict that southern Ontario has a 30 to 40 per cent chance of experiencing near-normal temperatures during this three-month period. Certain areas of the province, including the northeast and northwest, have a 50 to 60 per cent and 20 to 30 per cent chance, respectively. 

The last graph essentially confirms that southern Ontario is unlikely to see below-normal temperatures over the next three months. Based on the map, the GTA and most of southern Ontario have a 10 to 20 per cent chance of seeing below-normal temperatures between May and July.  

However, before summer fully takes hold, we might have to navigate a few more weeks of fluctuating weather and chilly temperatures. According to the long-range weather forecast from the Old Farmer's Almanac, May in southern Ontario could bring periods of cooler-than-normal temperatures. 

While temperatures are expected to warm up between May 10 and 16, the week of May 17 to 25 (which includes the Victoria Day long weekend) could bring chilly conditions along with a few showers. 

Overall, the Almanac predicts that southern Ontario will see an average May temperature of 11 C (approximately 1 C below the seasonal average). Precipitation totals are expected to be around 90 mm, which is 30 mm above average in the north, and 10 mm below average in the south.