The record high temperature of 29.6 C for September 22 was unofficially broken at 3pm Friday, as the mercury climbed to 30.4 C (86 F) at Sarnia Chris Hadfield Airport.
The humidex was also hovering around the 40 C mark.
Environment Canada issued a heat warning at mid-afternoon Friday with humidex values also expected to approach 40 C on Saturday and Sunday.
The agency says while extreme heat affects everyone -- the risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors.
Residents are encouraged to reduce heat risk by scheduling outdoor activities during the coolest parts of the day.
It's advised that we never leave people or pets inside a parked vehicle and people working outdoors are encouraged to take regularly scheduled breaks in a cool place.
Environment Canada Meteorologist Geoff Coulson says record highs could topple over the next four days.
"The record for Friday was 29.6 C (79 F) set on this day last year," says Coulson. "Highs Saturday and Sunday could hit 31 C (88 F). The record high for September 23, was 29 C (84 F) set in 2004 and 30.6 C (86 F) is the previous record for September 24."
Monday's record high could fall as well. The previous record was 30.3 C (86 F) in 2007.
Fall officially arrived at 4:02pm Friday afternoon. -With files from Lee Michaels
