Much of southern Ontario remains under a heat warning as 'hot and humid' air mass makes it feel like 40C

Toronto skyline. (The Canadian Press/Michelle Siu)

Several parts of the province, including much of the GTHA, remain under a heat warning as a "hot and humid" air mass is making it feel like 40 C.

In the Golden Horseshoe area, Toronto, Hamilton, Burlington-Oakville, Caledon, Halton Hills-Milton, London-Parkhill-Eastern Middlesex County, Mississauga-Brampton, Newmarket-Georgina-Northern York Region, Niagara Falls-Welland-Southern Niagara Region, Pickering-Oshawa-Southern Durham Region, St. Catharines, Grimsby-Northern Niagara Region, Uxbridge-Beaverton-Northern Durham Region, and Vaughan-Richmond Hill-Markham are affected by the “heat event,” which is expected to continue into Tuesday night when a cooler air mass is expected to arrive.

The warning also affects a number of regions in the northern and eastern parts of the province.

Environment Canada is advising that there won’t be much relief at night as minimum temperatures are expected to be near 20 degrees Celsius. Daytime maximum temperatures are expected to reach about 32 C.

“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 agency said.

Extreme heat can affect everyone’s health and Environment Canada is urging people to drink plenty of water regularly, even before they feel thirsty to decrease their risk of dehydration, limit direct sun exposure, and never leave people, especially children or pets, inside a parked vehicle.

People are also being advised to ask a health professional, like as a pharmacist or physician, how medications or health conditions can affect your risk in the heat, and to avoid using the oven by eating cool, light meals when it is hot outside.

Toronto was under a severe thunderstorm watch on Sunday afternoon, but that has since been cancelled.