Toronto and the GTHA are set to experience a heat event for the next several days starting Sunday.

Environment Canada has issued a heat warning for most of southern Ontario with temperatures expected to reach 30 C and feeling more like 40 when humidex values are factored in.

“Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high risk category,” the national weather service said in a statement.

“Drink plenty of water regularly, even before you feel thirsty to decrease your risk of dehydration. Limit direct sun exposure and never leave people, particularly children, or pets inside a parked vehicle.”

Similar warnings are also in effect for Aurora, Newmarket and Barrie to the north, all the way to Oshawa in the east, Mississauga, Brampton, Burlington, Oakville, Hamilton and the Niagara Penninsula.

There will be little relief at night as the warm and muggy conditions will keep temperatures hovering around 20 C.

A cooler airmass is expected to move into the region starting Tuesday night.