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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with readings persisting from 20 to 40 degrees below zero for multiple weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in half a century.

Prolonged Freeze in the Deep Minus Forties

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse similarly reported ten separate nights when temperatures dropped below -30C.

This Arctic air mass pushed further southward during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

The day after Christmas was forecast to deliver readings no higher than -20 Celsius in numerous areas, encompassing cities from Edmonton to Quebec.

Likely to Linger Through Early January

This harsh winter weather is expected to continue into the new year. There are warnings of possible electrical grid strain in Yukon territory soon, as the territory’s power grid comes under strain from peak power usage levels.

The lengthy cold snap originates from the polar vortex remaining anchored above Canadian territory through December, enabling a surge of icy Arctic winds to descend. In the coming week, forecasts indicate this cold air will pull back northward slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.

Pronounced Disparity with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. In many areas, conditions felt more typical of April or May rather than the end of December.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

Heat-Dome Effect Fuels Warmth

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with abnormal warmth projected to move through the American Southeast soon.

This heat is being driven by a powerful high-altitude ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This pattern establishes a broad area of high pressure across much of the continent, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.