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An intense cold spell has seized a severe and lengthy Arctic outbreak, with temperatures hovering between -20C and -40C for weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, marking its chilliest December reading in nearly five decades.

Enduring Chill of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse similarly reported 10 nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C in numerous areas, encompassing cities from Edmonton to Quebec.

Expected to Continue Through Early January

The frigid conditions are predicted to linger into the new year. 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 peak power usage levels.

The lengthy cold snap originates from the Arctic vortex settling across the northern part of the continent this month, enabling a surge of icy Arctic winds to descend. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.

Pronounced Disparity to American Heat

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. Across wide regions, the atmosphere was more akin to late spring than late December.

Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, 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 Sustains High Temperatures

Unseasonable heat is predicted to persist on December 26th and into the weekend, with atypical high temperatures expected to spread through the American Southeast soon.

The warmth has been fuelled by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, 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. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.