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Northern Canada has been gripped by an intense and prolonged cold spell, with thermometers lingering in the minus 20 to minus 40 Celsius range for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in nearly five decades.

Prolonged Freeze of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights below -40C, with Mayo plunging to -50.4C on Monday. The capital, Whitehorse, likewise saw 10 nights when temperatures dropped below -30C.

The bitter chill extended its reach south over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C across many regions, from Edmonton in the west to Quebec in the east.

Expected to Continue Through Early January

The frigid conditions are predicted to linger for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the system endures record-high pressure from historically high electricity consumption.

This extended freeze is the result of the polar vortex remaining anchored above Canadian territory through December, enabling a surge of icy Arctic winds to descend. 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.

Dramatic Difference with US Warmth

In stark contrast, parts of the US experienced historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. 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. The capital of Oklahoma soared to 25C on Christmas Day, surpassing the previous peak of 22C set in 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

Heat-Dome Effect Fuels Warmth

Above-average warmth is expected to continue on December 26th and into the weekend, with unseasonable heat forecast to sweep across the southeastern US in the coming days.

The unseasonable temperatures are powered by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. Such a configuration results in a widespread high-pressure system blanketing a significant part of the landmass, which holds warm air close to the ground. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.