The temperature in Windsor on Boxing Day hit 14.1 Celsius, beating the previous record of 13.3 in 2008.
Sarnia also hit a record 12 Celsius.
Environment Canada said the warmer weather isn't going anywhere fast.
"The temperatures should be still above normal until close to the end of the year," said Sherry Williams, metrologist with Environment Canada. "As we get into the new year, temperatures should get closer to normal values."
Snow is finally in the forecast for early next week.