Environment Canada has issued a heat warning for Sarnia-Lambton for the next couple of days.
Meteorologist Geoff Coulson says temperatures are expected to be near 32 C (90 F) Wednesday and Thursday with overnight lows near 20 C (68 F), providing little relief from the heat.
"We're looking at a fairly broad area of winds coming up from the south and the southwest and those winds have been bringing this warmer than normal airmass and humidity up from the american deep south," he says.
"We are going to see a break in the weather pattern for Friday when a front moves through, kicks off some shower activity and maybe some thunderstorms, and that should bring us some relief for the weekend. Highs expected on Saturday and Sunday about 24 C (75 F), a little cooler than our normal high of 27 C (81 F) for this time of year and also much more comfortable levels of humidity."
Humidex values near 40 C (104 F) are forecast for Wednesday.
While heat can put everyone at risk from heat illness, the national weather agency says health risks are greatest for - older adults, infants and young children, people with chronic illnesses such as breathing difficulties, heart conditions, people who work or exercise in the heat, homeless people and people without access to air conditioning.
It's recommended you drink plenty of liquids especially water before you feel thirsty to decrease your risk of dehydration. Thirst is not a good indicator of dehydration.