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Northern Canada has been gripped by an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in nearly five decades.

Prolonged Freeze Below -40C

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. Whitehorse similarly reported ten separate nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

December 26th was anticipated to usher in readings no higher than -20 Celsius through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.

Expected to Continue Through Early January

The severe cold is forecast to persist for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the territory’s power grid comes under strain from peak power usage levels.

The lengthy cold snap originates from the Arctic vortex settling across the northern part of the continent this month, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over America and reach into portions of southern Canada.

Pronounced Disparity to American Heat

Meanwhile, in a dramatic contrast, areas of the United States saw the hottest December 25th in their history as temperatures soared about 15-30C above the seasonal average. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, surpassing the previous peak of 22C set in 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

High-Pressure System Drives the Heat

Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with unseasonable heat forecast to sweep through the American Southeast soon.

This heat is being driven by a strong upper-level ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure across much of the continent, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.