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An intense cold spell has seized a severe and lengthy Arctic outbreak, with readings persisting between -20C and -40C 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 half a century.

Consecutive Nights of Extreme Cold

Meanwhile, Mayo and Dawson endured over two straight weeks of nights below -40C, with Mayo plunging to -50.4C on Monday. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.

The deep freeze spread farther south through Christmas week. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

The day after Christmas was forecast to deliver lows of at least -20C across many regions, from Edmonton in the west to Quebec in the east.

Expected to Continue Through Early January

The severe cold is forecast to persist through the start of January. Officials have warned that the Yukon could face electricity outages soon, as the system endures record-high pressure from historically high electricity consumption.

The lengthy cold snap originates from a stationary polar vortex across the northern part of the continent this month, 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.

Stark Contrast with US Warmth

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. In many areas, conditions felt more typical of April or May rather than the end of December.

A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

High-Pressure System Drives the Heat

Above-average warmth is expected to continue on December 26th and into the weekend, with abnormal warmth projected to move across the southeastern US in the coming days.

This heat is being driven by a powerful high-altitude ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, which holds warm air close to the ground. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.