Sarnia's previous record low temperatures, dating back some 50 years, were shattered by bone-chilling cold Wednesday night and Thursday morning.
The mercury at Chris Hadfield Airport dropped to -23.5 C (-9 F) at 11 p.m. Wednesday and then fell further to -24.4 C by 8 a.m. Thursday.
The previous record lows for January 30, and January 31, in Sarnia were -21.7 C in 1966, and -20.6 C in 1971.
Environment Canada's extreme cold warning remained in effect Thursday but an end to the bitter cold snap is in sight with unseasonably mild temperatures by early next week.
Some slight moderation in the wind chill is expected Thursday night as winds become light but it will still be dangerously cold with the risk of frostbite within minutes.
A high of -13 C is forecast for Friday with a wind chill of -16 C in the afternoon, then temperatures will climb through the weekend to a high of 7 C (45 F) Monday.
Weather experts say this week's prolonged, extreme cold is due to a split in the polar vortex, which is a mass of cold air that normally stays bottled up in the Arctic.
The split has allowed the frigid air to spill much farther south than usual.
