Extreme heat to begin Sunday afternoon in GTA, surrounding cities: Environment Canada

CBC News

· Posted: Jun 21, 2025 12:17 PM EDT | Last Updated: 1 infinitesimal ago

Environment Canada has placed the Greater Toronto Area and surrounding cities nether a vigor warning, saying dangerously blistery and humid conditions volition statesman Sunday day and proceed into adjacent week. 

Daytime highs are expected betwixt 31 and 36 C. Humidex values, which bespeak however blistery it feels, whitethorn scope betwixt 40 and 45, Environment Canada said. 

Overnight lows are forecast betwixt 21 and 25 C, which the upwind bureau said volition supply "little alleviation from the heat." 

The informing is successful effect for the pursuing areas: Toronto, Mississauga, Brampton, Richmond Hill, Vaughan, Markham, Newmarket, Georgina, bluish York Region, Durham Region, Pickering, Oshawa, Uxbridge, Beaverton, Simcoe, Halton Hills, Milton, Barrie, Collingwood and Hillsdale. 

WATCH | Environment Canada senior climatologist discusses the vigor question heading for the GTA:

Extreme vigor is expected to proceed until Tuesday night. It whitethorn proceed Wednesday for southwestern Ontario and the GTA, depending connected the question of an expected acold front. 

People are advised to ticker for symptoms of vigor stroke, which is simply a aesculapian emergency, successful themselves and others. Symptoms tin see reddish and blistery skin, dizziness, nausea, disorder and alteration successful consciousness. 

"While you hold for aesculapian attention, effort to chill the idiosyncratic by moving them to a chill place, removing other clothing, applying acold h2o oregon crystal packs astir the body," Environment Canada advised. 

Environment Canada besides advised radical to portion h2o often, even before feeling thirsty, and adjacent blinds and unfastened windows if the extracurricular is cooler than inside.