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An intense cold spell has seized an intense and prolonged cold spell, with readings persisting in the minus 20 to minus 40 Celsius range for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading since 1975.

Enduring Chill of Extreme Cold

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 earlier this week. Whitehorse similarly reported ten separate nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

Boxing Day was expected to bring lows of at least -20C in numerous areas, encompassing cities from Edmonton to Quebec.

Expected to Continue Through Early January

This harsh winter weather is expected to continue 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 historically high electricity consumption.

This extended freeze is the result of the Arctic vortex settling above Canadian territory through December, which funnels frigid northern air southward. In the coming week, forecasts indicate this cold air will pull back northward gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Stark Contrast Compared to Stateside Temperatures

Meanwhile, in a dramatic contrast, areas of the United States saw their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

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. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

Heat-Dome Effect Drives the Heat

Above-average warmth is expected to continue 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 reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. Such a configuration results in a widespread high-pressure system over a large portion of North America, which holds warm air close to the ground. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.