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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 weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, marking its chilliest December reading since 1975.

Consecutive Nights Below -40C

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C at the start of the week. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.

The bitter chill extended its reach south during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

December 26th was anticipated to usher in lows of at least -20C across many regions, encompassing cities from Edmonton to Quebec.

Expected to Continue For Days to Come

The frigid conditions are predicted to linger into the new year. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as its energy infrastructure faces unprecedented demand from record-high energy demand.

The lengthy cold snap originates from the polar vortex remaining anchored across the northern part of the continent this month, enabling a surge of icy Arctic winds to descend. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Stark Contrast Compared to Stateside Temperatures

In stark contrast, parts of the US experienced their warmest Christmas Day on record as the mercury climbed roughly 15 to 30 degrees above typical averages. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

Several states set Christmas Day temperature records. In Oklahoma, Oklahoma City hit 25C on Tuesday, topping the prior high mark of 22 degrees established over forty years ago. Urban centers like Austin, Dallas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Heat-Dome Effect Drives the Heat

Unseasonable heat is predicted to persist on December 26th and into the weekend, with abnormal warmth projected to move into the south-eastern states later in the week.

The warmth has been fuelled by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, trapping warm air near the surface. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.