The Middlesex London Health Unit is issuing the fifth Cold Weather Alert of the season.
Environment Canada is predicting the overnight low will drop to -16C. Temperatures tomorrow are expected to hover around the -15C mark, with the wind chill making it feel more like -25C.
The alert will be in effect until Friday, February 6, when the daytime high is forecasted to reach -6C.
Health officials warn that if you plan on heading outdoors you should be dressed for the weather.
Frostbite is possible within only a few moments of stepping outside.
