Large parts of Ontario are sweating under an extended heat wave, where temperatures could hit 45 C on the humidex, as the City of Toronto is issued with an orange heat warning.
Early Monday morning, Environment Canada issued heat warnings for much of southwestern Ontario, as well as large portions of the east, stretching all the way up to Hearst and Cochrane in the north.
“A long duration heat event begins today,” a warning issued for the Chatham-Kent area read.
“Maximum temperatures of 30 to 32 degrees Celsius and humidex values of 37 to 42 are expected today.”
The yellow warning said heat and humidity would only worsen on Tuesday, hitting a maximum temperature of between 31 and 36 C. That will feel closer to 45 C when the humidity is factored in.
Global News meteorologist Peter Quinlan said the temperatures in and around Toronto would be lower — but not by much.

Get daily National news
Get daily Canada news delivered to your inbox so you’ll never miss the day’s top stories.
“We’re expecting highs in the mid-30s starting tomorrow and hitting 30-degree highs right up until the weekend with humidex values into the low-to-mid 40s,” he said.
“This dangerous heat will require you to take extra precautions such as looking for cool, air-conditioned spaces, staying hydrated and cool as well.”
The heat wave is expected to last all week, according to Environment Canada, which is urging people to remain vigilant.
“Take action to protect yourself and others — extreme heat can affect everyone’s health,” the weather agency wrote.
“Determine if you or others around you are at greater risk of heat illness. Check on older adults, those living alone and other at-risk people in-person or on the phone multiple times a day.”
Later in the day, the yellow heat warning was upgraded to orange for parts of the province, including Toronto.
“The hottest days are expected to be Wednesday and Thursday, with maximum temperatures of 34 to 36 degrees Celsius expected,” it read. “Minimum temperatures of 21 to 24 degrees Celsius will provide little relief from the heat.”
The heat will also be punctuated with rain and thunderstorms.
© 2026 Global News, a division of Corus Entertainment Inc.


