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Northern Canada has been gripped by a severe and lengthy Arctic outbreak, with readings persisting from 20 to 40 degrees below zero for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in nearly five decades.

Prolonged Freeze Below -40C

In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights colder than minus 40 degrees, with Mayo plunging to -50.4C earlier this week. The capital, Whitehorse, likewise saw ten separate nights when temperatures dropped below -30C.

The bitter chill extended its reach south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

The day after Christmas was forecast to deliver readings no higher than -20 Celsius across many regions, including Edmonton, Montreal, Ottawa and Quebec.

Expected to Continue Through Early January

The severe cold is forecast to persist through the start of January. There are warnings of possible electrical grid strain in Yukon territory soon, as the system endures record-high pressure from peak power usage levels.

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. 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

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

Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Urban centers like Austin, Dallas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Heat-Dome Effect Sustains High Temperatures

Unseasonable heat is predicted to persist for the remainder of the week and beyond, with atypical high temperatures expected to spread into the south-eastern states later in the week.

This heat is being driven by a strong upper-level ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure across much of the continent, which holds warm air close to the ground. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.