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Northern Canada has been gripped by a bitter and extended period of frigid weather, with thermometers lingering between -20C and -40C for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day in half a century.

Consecutive Nights in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. Whitehorse similarly reported a series of ten nights when the cold dipped under -30 Celsius.

This Arctic air mass pushed further southward during the holiday season. 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, including Edmonton, Montreal, Ottawa and Quebec.

Expected to Continue Through Early January

The severe cold is forecast to persist into the new year. Officials have warned that the Yukon could face electricity outages soon, as the system endures record-high pressure from historically high electricity consumption.

The prolonged chill has been caused by the Arctic vortex settling across the northern part of the continent this month, enabling a surge of icy Arctic winds to descend. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across the United States and penetrate southern Canadian regions.

Stark Contrast Compared to Stateside Temperatures

In stark contrast, parts of the US experienced the hottest December 25th in their history 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.

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 Fuels Warmth

Above-average warmth is expected to continue for the remainder of the week and beyond, with abnormal warmth projected to move into the south-eastern states later in the week.

This heat is being driven by a robust atmospheric ridge reaching from the arid southwest across the continent, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, which holds warm air close to the ground. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.