Ontario Braces for Multi-Day Heat Event as Temperatures Soar

Much of Ontario is facing a prolonged period of dangerous heat on Tuesday, with a heightened risk of heat-related illnesses, including heat exhaustion and possible heat stroke.

The most intense conditions are expected across southwestern Ontario, where a multi-day heat event is already underway. Daytime highs are forecast to reach between 34 and 36 C, while humidex values are expected to climb into the low-to-mid 40s. Overnight temperatures will offer little relief, remaining between 22 and 24 C.

The heat is also expected to spread into the Golden Horseshoe on Tuesday. Temperatures near 34 C and humidex values in the low 40s are forecast, with warm overnight lows ranging from 22 to 24 C.

Elsewhere in southern Ontario, a multi-day heat event is expected to begin Tuesday, bringing temperatures between 31 and 33 C and humidex values in the upper 30s to low 40s. Overnight temperatures are expected to remain between 21 and 23 C.

Northern Ontario is also expected to experience unseasonably hot conditions. Areas in northwestern Ontario and regions north and east of Lake Superior could see temperatures ranging from 29 to 31 C, accompanied by humidex values in the mid-to-upper 30s. Overnight lows are forecast between 18 and 20 C. However, forecasters note some uncertainty, as showers moving through the region could keep daytime temperatures somewhat cooler.

In northeastern, central and eastern Ontario, temperatures between 28 and 30 C are forecast, with humidex values reaching the mid-to-upper 30s. Overnight lows are expected to range from 18 to 20 C. Similar to northern sections of the province, uncertainty remains due to the possibility of showers affecting daytime heating.