Environment Canada is issuing a heat warning, as it predicts the longest and most significant heat wave of the summer is on its way to southwestern Ontario.
The agency says a hot and humid airmass is coming up from the US Tuesday afternoon, pushing temperatures to 37 C (99 F) with the humidex.
It's expected to stay humid overnight Tuesday and into Wednesday, where humidex values stretch near 45 C (113 F).
Environment Canada says relief from the humidity may come Friday, when a weak cold front, along with a chance of showers and thunderstorms moves through the area.
