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A prolonged deep freeze has enveloped an intense and prolonged cold spell, 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, marking its chilliest December reading in half a century.

Prolonged Freeze Below -40C

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. The capital, Whitehorse, likewise saw a series of ten nights when temperatures dropped below -30C.

This Arctic air mass pushed further southward during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.

Likely to Linger Through Early January

This harsh winter weather is expected to continue through the start of January. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the system endures record-high pressure from peak power usage levels.

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 allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Dramatic Difference Compared to Stateside Temperatures

Conversely, sections of America recorded their warmest Christmas Day on record as the mercury climbed roughly 15 to 30 degrees above typical averages. For numerous locations, the weather resembled a spring day in April or May rather than the end of December.

Multiple states established new Christmas temperature highs. 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 similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Fuels Warmth

Unseasonable heat is predicted to persist 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 robust atmospheric ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. 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.