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Northern Canada has been gripped by an intense and prolonged cold spell, with readings persisting in the minus 20 to minus 40 Celsius range for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, representing its most frigid December day in nearly five decades.

Consecutive Nights in the Deep Minus Forties

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row below -40C, with Mayo plunging to -50.4C at the start of the week. Whitehorse similarly reported ten separate nights when temperatures dropped below -30C.

This Arctic air mass pushed further southward over the festive period. Christmas night saw Edmonton's temperatures plummet below minus 28C.

The day after Christmas was forecast to deliver minimum temperatures of at least minus 20C across many regions, encompassing cities from Edmonton to Quebec.

Forecast to Persist Through Early January

The frigid conditions are predicted to linger through the start of January. There are warnings of possible electrical grid strain in Yukon territory soon, 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 over Canada for much of December, enabling a surge of icy Arctic winds to descend. Next week, the cold air mass is expected to retreat north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Stark Contrast to American Heat

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. In many areas, conditions felt more typical of April or May than late December.

Several states set Christmas Day temperature records. In Oklahoma, Oklahoma City hit 25C on Tuesday, surpassing the previous peak of 22C set in 1982. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

Atmospheric Ridge Fuels Warmth

Above-average warmth is expected to continue on December 26th and into the weekend, with abnormal warmth projected to move through the American Southeast soon.

The warmth has been fuelled by a powerful high-altitude ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure across much of the continent, effectively capping warm air at lower altitudes. As air sinks through the atmosphere, it compresses and heats further, allowing unusually warm temperatures to build.