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Northern Canada has been gripped by an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day since 1975.

Prolonged Freeze in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights below -40C, with Mayo experiencing a low of -50.4C on Monday. Whitehorse also recorded ten separate nights when temperatures dropped below -30C.

The deep freeze spread farther south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

Boxing Day was expected to bring minimum temperatures of at least minus 20C in numerous areas, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist Through Early January

The severe cold is forecast to persist into the new year. Officials have warned that the Yukon could face electricity outages in the coming days, as the territory’s power grid comes under strain from historically high electricity consumption.

This extended freeze is the result of 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 allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.

Stark Contrast to American Heat

Meanwhile, in a dramatic contrast, areas of the United States saw 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.

Several states set Christmas Day temperature records. In Oklahoma, Oklahoma City hit 25C on Tuesday, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.

Heat-Dome Effect Fuels Warmth

Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with unseasonable heat forecast to sweep into the south-eastern states later in the week.

This heat is being driven by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, which holds warm air close to the ground. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.