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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, 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, representing its most frigid December day in nearly five decades.

Enduring Chill in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row colder than minus 40 degrees, with Mayo experiencing a low of -50.4C earlier this week. The capital, Whitehorse, likewise saw a series of ten nights when temperatures dropped below -30C.

This Arctic air mass pushed further southward during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist Through Early January

The severe cold is forecast to persist into the new year. Authorities have cautioned about potential power failures in the Yukon soon, as the system endures record-high pressure from peak power usage levels.

This extended freeze is the result of the Arctic vortex settling over Canada for much of December, which funnels frigid northern air southward. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Stark Contrast to American Heat

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. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, surpassing the previous peak of 22C set in 1982. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.

Atmospheric Ridge Fuels Warmth

Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with atypical high temperatures expected to spread through the American Southeast soon.

The unseasonable temperatures are powered by a powerful high-altitude ridge reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.