Although there is still the possibility of showers and thunderstorms Wednesday, Environment Canada has lifted a severe thunderstorm watch for Sarnia-Lambton.
A heat warning remains in effect with a high of 30/86 and a humidex of 40/104.
The heat will end when a cold front moves into the area later on Wednesday.
Overnight lows will drop to 14/57 with a high Thursday of 20/68.