Lambton Public Health has issued an extended heat warning as hot and humid conditions are expected to persist into the weekend.
Environment Canada issued a heat warning for most parts of southwestern Ontario on Monday.
The heat wave was initially expected to continue through Thursday with the possibility of extending into Saturday.
The national weather agency is now forecasting a daytime high of 31 C, 88 F, both Friday and Saturday. Humidex values on Friday are expected to reach the high 30s.
As a reminder, the health unit has advised residents that it may be difficult to cool properly during times of high temperatures and humidity, which can lead to heat exhaustion or even heat stroke. Residents are encouraged to drink plenty of water and check on older family members or friends.