Much of southern Ontario, including the Toronto area, is under a heat warning with temperatures expected to surpass 30 C.
Environment Canada issued its fourth consecutive heat warning on Thursday, though the heat and humidity will not be as powerful as earlier in the week.
Meteorologists predict a high of 31 C by 4 a.m., but it will feel closer to 36 C with the humidex. The hot temperatures come a day after temperatures rocketed to 32 C, feeling like 40 C with the humidity, making Wednesday the hottest day of 2015.
The weather agency said the heat wave is caused by a hot air mass that moved into the region earlier this week and continues to hover over southern Ontario.
The mass is expected to pass by the weekend, with temperatures forecast to drop to 24 C on Saturday.
Residents of the affected areas are warned to watch for symptoms of heat illness including dizziness and fainting, headache, rapid breathing and decreased urination. Anyone who experiences the symptoms is advised to move to a cool place and drink liquids.
The following areas fall under the warning:
- Toronto
- Niagara
- Hamilton
- Halton-Peel
- York-Durham
- Belleville-Quinte-Northumberland
- Kingston-Prince Edward
- Stirling-Tweed-South Frontenac
- Brockville-Leeds and Grenville
- Ottawa-Gatineau
- Prescott and Russell
- Cornwall-Morrisburg
- Smiths Falls-Lanark-Sharbot Lake
