We can expect some relief from the heat and humidity Tuesday with the arrival of a cold front Monday night.
A heat warning remained in effect Monday with a forecast high of 32 C (90 F) and the humidex nearing 40 C (104 F).
Environment Canada meteorologist Peter Kimbell says the U.S. midwest and all of southern Ontario are feeling the heat.
"Everywhere you look, to the west, to the south, to the east, it's the same thing, very warm air coming up from the midwest United States," says Kimbell. "And that's going to continue until a cold front comes through tonight and will bring a bit of relief for tomorrow, not a lot of relief, the temperature tomorrow expected to be 25 C."
A humidex of 30 C (86 F) is forecast Tuesday.
Sunday's high of 32 C in Sarnia was just shy of the record high for June 11 of 32.2 C set in 1973.
The standing record for June 12 is 33 C set in 1988.
There is the chance of showers and thunderstorms Monday night and Tuesday.
While extreme heat can put everyone at risk from heat illnesses, health risks are greatest for older adults, infants and young children and people with chronic illnesses.
Residents are reminded to limit time spent outdoors and drink plenty of water.
Cooling centres are available across Sarnia-Lambton. Click here for a full list.
