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A prolonged deep freeze has enveloped an intense and prolonged cold spell, 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, marking its chilliest December reading in nearly five decades.

Prolonged Freeze in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C earlier this week. Whitehorse also recorded a series of ten nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south over the festive period. 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, including Edmonton, Montreal, Ottawa and Quebec.

Expected to Continue into the New Year

The severe cold is forecast to persist through the start of January. Officials have warned that the Yukon could face electricity outages over the next several days, as its energy infrastructure faces unprecedented demand from record-high energy demand.

The lengthy cold snap originates from a stationary polar vortex across the northern part of the continent this month, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Stark Contrast Compared to Stateside Temperatures

Conversely, sections of America recorded historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. For numerous locations, the weather resembled a spring day in April or May rather than the end of December.

Several states set Christmas Day temperature records. In Oklahoma, Oklahoma City hit 25C on Tuesday, surpassing the previous peak of 22C set in 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Fuels Warmth

Above-average warmth is expected to continue through Boxing Day and the days ahead, with abnormal warmth projected to move across the southeastern US in the coming days.

This heat is being driven by a robust atmospheric ridge reaching from the arid southwest across the continent, which generates a heat-dome phenomenon. Such a configuration results in a widespread high-pressure system over a large portion of North America, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.