So far, during winter 2023-24 in North America, the prevailing climate is exceptionally mild across Canada and the Northern U.S. However, an 11-day period of hostile cold interrupted the warmth on Jan. 11-21 thanks to cross polar arctic airflow from Siberia. Similarly, Europe has observed a very mild winter season. There have been brief cold weather exceptions, one in early December and a second Jan. 7-14 featuring arctic air.