Sarnia-Lambton residents are being told to prepare for what could be the most significant heat wave of the summer so far.
Environment Canada has issued a heat warning for much of southern Ontario.
Forecasters say a hot and humid air mass will move in from the U.S. Tuesday afternoon, with temperatures reaching the low 30s. Humidex values are expected to rise to the mid-30s.
It will become increasingly humid Tuesday night, with overnight temperatures near 20 C in most areas. The hot and humid conditions under partly to mostly sunny skies are expected to continue through Friday.
Humidex values peaking in the low 40s are expected beginning Wednesday.
Environment Canada says relief from the daytime heat is possible in areas near the shorelines of the Great Lakes if lake breezes develop.
Relief is expected Friday night with the arrival of a weak cold front along with showers and thunderstorms.
Lambton Public Health has cooling centres set up in the heat and humidity. You can find the list here.
