The 32-year-old record high temperature for Christmas Eve in Sarnia was shattered Wednesday.
The mercury at Chris Hadfield Airport rose to 12 C (54 F) by 4pm.
The previous record for December 24 was 9.9 C, set in 1982.
The temperature rose six degrees between 2pm and 4pm as winds shifted from northwest to south-southeast.
It promptly fell back to 5 C by 5pm on another wind shift that brought rain, thunder and lightning.
The unusually mild weather was in advance of an intense low pressure system packing high winds.
A wind warning was in effect for Christmas Eve.
