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Northern Canada has been gripped by a severe and lengthy Arctic outbreak, with temperatures hovering between -20C and -40C for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in half a century.

Consecutive Nights of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights colder than minus 40 degrees, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported 10 nights when readings fell to minus 30 degrees or lower.

The deep freeze spread farther south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C across many regions, from Edmonton in the west to Quebec in the east.

Likely to Linger For Days to Come

The severe cold is forecast to persist into the new year. Officials have warned that the Yukon could face electricity outages soon, as the territory’s power grid comes under strain from peak power usage levels.

This extended freeze is the result of a stationary polar vortex across the northern part of the continent this month, which funnels frigid northern air southward. In the coming week, forecasts indicate this cold air will pull back northward slowly, permitting warmer Pacific winds to flow over America and reach into portions of southern Canada.

Stark Contrast with US Warmth

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. In many areas, conditions felt more typical of April or May than late December.

Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, topping the prior high mark of 22 degrees established over forty years ago. Urban centers like Austin, Dallas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

Heat-Dome Effect Fuels Warmth

Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with abnormal warmth projected to move through the American Southeast soon.

This heat is being driven by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, trapping warm air near the surface. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.