Parts of southern Ontario, including the Greater Toronto Area, the City of Hamilton and Niagara Region are under a Heat Warning.

It’s the first Heat Warning of the season issued by Environment Canada for southern Ontario.

Temperature highs of 31 degrees are expected for Sunday, and 32 degrees on Monday.

Humidex readings could reach 36 on Sunday, and even close to 40 on Monday.

Environment Canada says such temperatures can be dangerous for young children, older adults, pregnant women and anyone with a chronic illness.

In heat like this it’s a good idea to drink plenty of water even before you’re actually thirsty, and of course, try to stay in a cool place.