Heat warning issued for Toronto and GTA beginning Monday

Environment Canada has issued a yellow-level warning for heat in Toronto and surrounding areas beginning on Monday. Temperatures are expected to reach a high of 30 to 36 C with humidex values of 38 to 45 C, the national weather agency predicts. The hot and humid forecast is expected to last until Wednesday or Thursday [...]

Heat warning issued for Toronto and GTA beginning Monday Posted July 12, 2026 6:01 pm. Last Updated July 12, 2026 6:02 pm. Environment Canada has issued a yellow-level warning for heat in Toronto and surrounding areas beginning on Monday.

Temperatures are expected to reach a high of 30 to 36 C with humidex values of 38 to 45 C, the national weather agency predicts. The hot and humid forecast is expected to last until Wednesday or Thursday evening. “Tuesday will mark the peak of this heat event.

Maximum temperatures are expected to reach near 36 degrees Celsius in some areas,” reads an Environment Canada notice. “Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high-risk category.” “Take action to protect yourself and others – extreme heat can affect everyone’s health,” it added.

The heat warning has been issued for Toronto, Pickering, Oshawa, Vaughan, Richmond Hill, Markham, Peel, Halton, Hamilton and Niagara. “Watch for the early signs of heat exhaustion in yourself and others,” officials added. “Signs may include headache, nausea, dizziness, thirst, dark urine and intense fatigue.

Stop your activity and drink water.”