The threat violent thunderstorms hovered part of the day over the south of the province (archives).
Environment Canada issued successive alerts and watches on Wednesday for heat, thunderstorms violent and even tornadoes at times in the southern regions of the province.
By late evening, severe thunderstorm warnings and watches still affected a dozen regions, but all tornado warnings had been lifted.
During the day, temperatures soared into the 30s and the Humidex Index approached 40 in many areas.
Authorities advise the public to go swimming or stay in an air-conditioned place to avoid heat stroke.
Very hot and humid air can also cause heat stroke. deterioration in air quality and bring the Air Quality Health Index near the high risk category, according to Environment Canada.
The federal agency is advising the public to watch for heat-related symptoms such as swelling, rash, cramps, fainting or exhaustion.
Look for a cool place – such as tree shade, swimming pool, shower or bath – or an air-conditioned place like a public building, recommends Environment Canada. Never leave people or animals in a parked vehicle.
Slightly cooler weather is expected Thursday in Greater Toronto and Niagara, in particular.
On the other hand, in the Southwest, the episode of oppressive heat could last until Sunday.