Residents of Windsor-Essex and Chatham-Kent can expect the muggy weather to last all weekend.
Late Saturday morning Environment Canada issued a heat warning for the two counties with no relief in sight until Sunday night.
Daytime temperatures for the weekend are expected to reach the low 30s with the humidex making it feel more like the low 40s. Overnight, between Saturday and Sunday, temperatures will remain above 20 degrees.
The heat event is expected to end Sunday night with slightly cooler temperatures expected on Monday following a cold front.
"Hot and humid air can also bring deteriorating air quality," the weather agency warned.
People are advised to watch for heat illness over the weekend, symptoms can include:
• rapid breathing and heartbeat
• extreme thirst
• decreased urination with unusually dark urine
Drinking plenty of water, even before you feel thirty, is one of the best ways to stay cool during a heat event.