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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with readings persisting between -20C and -40C for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, representing its most frigid December day since 1975.

Prolonged Freeze of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row colder than minus 40 degrees, with Mayo plunging to -50.4C on Monday. Whitehorse also recorded 10 nights when the cold dipped under -30 Celsius.

The deep freeze spread farther south over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

Boxing Day was expected to bring lows of at least -20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.

Likely to Linger Through Early January

The frigid conditions are predicted to linger for the foreseeable future. Officials have warned that the Yukon could face electricity outages in the coming days, as the system endures record-high pressure from historically high electricity consumption.

The prolonged chill has been caused by the polar vortex remaining anchored across the northern part of the continent this month, which funnels frigid northern air southward. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over the US and into parts of southern Canada.

Pronounced Disparity with US Warmth

Conversely, sections of America recorded historically high temperatures for Christmas 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.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, surpassing the previous peak of 22C set in 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

High-Pressure System Sustains High Temperatures

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with unseasonable heat forecast to sweep across the southeastern US in the coming days.

The unseasonable temperatures are powered by a powerful high-altitude ridge reaching from the arid southwest across the continent, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, which holds warm air close to the ground. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.