The temperature at Sarnia's Chris Hadfield Airport early Saturday morning dropped to its lowest level in 50 years for the 19th of September.
Environment Canada said the mercury dipped to 1.1 C, 34 F, easily beating the previous mark of 1.7 C set in 1969.
A frost advisory remained in effect Saturday with another low near zero forecast. The normal minimum temperature in Sarnia at this time of year is 10 C, 50 F.
Patchy frost is expected again Saturday night into Sunday morning as a large Arctic high pressure area settles in over the Great Lakes.
The weather agency recommends preventative measures be taken to protect frost-sensitive plants and trees.
Frost advisories are issued when temperatures are expected to reach the freezing mark during the growing season, leading to potential damage and destruction to plants and crops.
Fall officially arrives Tuesday, September 22 at 9:31 a.m.