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An intense cold spell has seized an intense and prolonged cold spell, with temperatures hovering in the minus 20 to minus 40 Celsius range for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading since 1975.

Consecutive Nights of Extreme Cold

Meanwhile, Mayo and Dawson endured 16 consecutive nights below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.

The deep freeze spread farther south during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

Boxing Day was expected to bring lows of at least -20C across many regions, from Edmonton in the west to Quebec in the east.

Likely to Linger into the New Year

This harsh winter weather is expected to continue through the start of January. Officials have warned that the Yukon could face electricity outages in the coming days, as its energy infrastructure faces unprecedented demand from peak power usage levels.

This extended freeze is the result of the polar vortex remaining anchored over Canada for much of December, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across the United States and penetrate southern Canadian regions.

Stark Contrast with US Warmth

In stark contrast, parts of the US experienced the hottest December 25th in their history as readings skyrocketed 15 to 30 degrees Celsius above normal. For numerous locations, the weather resembled a spring day in April or May than late December.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, surpassing the previous peak of 22C set in 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

High-Pressure System Fuels Warmth

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with abnormal warmth projected to move into the south-eastern states later in the week.

This heat is being driven by a robust atmospheric ridge reaching from the arid southwest across the continent, which generates a heat-dome phenomenon. This pattern establishes a broad area of high 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.