Sarnia-Lambton is under a heat warning as a hot and increasingly humid air mass takes hold.
Daytime high temperatures are expected to range from 31 C to 34 C with overnight lows of 20 C to 24 C.
Humidex values in the high 30s to low 40s are forecast for Saturday and Sunday.
Environment Canada said hot and humid air can also bring deteriorating air quality and the air quality health index could approach the high-risk category.
We're being urged to watch for the effects of heat illness including swelling, rash, cramps, fainting, heat exhaustion, heatstroke and the worsening of some health conditions.
Outdoor workers should take regularly scheduled breaks in a cool place, and people or pets should never be left inside a parked vehicle.
Heat warnings are issued when very high temperature or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.
More information from Lambton Public Health can be found here.