Although most of Canada has enjoyed a warmer than normal Fall, December brought an abrupt transition. This is due to part of the polar vortex located over northern Canada, providing artic air across most of the country.
For the third year in a row, the primary driver for Canada’s winter weather pattern will be La Niña. The typical weather pattern during La Niña winters, brings frigid weather across western Canada and milder temperatures from the Great Lakes to Atlantic Canada. However, at times it is expected that the frigid weather will shift east, and stretch from the eastern Prairies to Quebec with milder weather across B.C. and Alberta, much like the weather pattern last year.
https://www.theweathernetwork.com/ca/news/article/canada-2023-winter-weather-forecast