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An intense cold spell has seized an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in half a century.

Enduring Chill Below -40C

In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. The capital, Whitehorse, likewise saw 10 nights when temperatures dropped below -30C.

The bitter chill extended its reach south through Christmas week. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

The day after Christmas was forecast to deliver lows of at least -20C across many regions, encompassing cities from Edmonton to Quebec.

Likely to Linger For Days to Come

The frigid conditions are predicted to linger 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 polar vortex remaining anchored across the northern part of the continent this month, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.

Pronounced Disparity Compared to Stateside Temperatures

Conversely, sections of America recorded historically high temperatures for Christmas as temperatures soared about 15-30C above the seasonal average. In many areas, conditions felt more typical of April or May rather than the end of December.

A number of states broke historical records for December 25th warmth. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Heat-Dome Effect Drives the Heat

Unseasonable heat is predicted to persist on December 26th and into the weekend, with abnormal warmth projected to move across the southeastern US in the coming days.

The unseasonable temperatures are powered by a strong upper-level ridge extending from the desert south-west towards the north and east, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure across much of the continent, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.