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An intense cold spell has seized an intense and prolonged cold spell, with thermometers lingering from 20 to 40 degrees below zero for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading in half a century.

Enduring Chill in the Deep Minus Forties

Meanwhile, Mayo and Dawson endured over two straight weeks of nights colder than minus 40 degrees, with Mayo experiencing a low of -50.4C earlier this week. The capital, Whitehorse, likewise saw ten separate nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south through Christmas week. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

Boxing Day was expected to bring minimum temperatures of at least minus 20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist For Days to Come

The severe cold is forecast to persist through the start of January. Authorities have cautioned about potential power failures in the Yukon soon, as the territory’s power grid comes under strain from historically high electricity consumption.

The prolonged chill has been caused by the polar vortex remaining anchored over Canada for much of December, allowing bitter Arctic air to spill south. In the coming week, forecasts indicate this cold air will pull back northward slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.

Pronounced Disparity Compared to Stateside Temperatures

In stark contrast, parts of the US experienced their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

A number of states broke historical records for December 25th warmth. 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

Unseasonable heat is predicted to persist on December 26th and into the weekend, with unseasonable heat forecast to sweep into the south-eastern states later in the week.

The warmth has been fuelled by a powerful high-altitude 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 blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.