Environment Canada has issued a heat warning for the Niagara Region.
A hot and increasingly humid air mass will affect south-central Ontario and the Greater Toronto Area today through at least Sunday.
Slightly cooler and less humid conditions may arrive on Monday.
Daytime highs in the Niagara region will be 31 to 34 degrees celsius, with overnight lows 20 to 24 degrees celsius.
Humidex values will incerase tomorrow to the low 40's.
Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high risk category.
Residents are advised to watch for the effects of heat illness, which include swelling, rash, cramps, fainting, heat exhaustion, heat stroke and the worsening of some health conditions.
Also always a good reminder to never leave people or pets inside a parked vehicle.