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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with temperatures hovering in the minus 20 to minus 40 Celsius range for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading since 1975.

Enduring Chill Below -40C

Meanwhile, Mayo and Dawson endured sixteen nights in a row dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C on Monday. Whitehorse also recorded a series of ten nights when temperatures dropped below -30C.

The bitter chill extended its reach south during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

December 26th was anticipated to usher in lows of at least -20C through a wide swath, from Edmonton in the west to Quebec in the east.

Expected to Continue into the New Year

This harsh winter weather is expected to continue through the start of January. There are warnings of possible electrical grid strain in Yukon territory in the coming days, as the territory’s power grid comes under strain from peak power usage levels.

The lengthy cold snap originates from the polar vortex remaining anchored above Canadian territory through December, allowing bitter Arctic air to spill south. 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.

Stark Contrast with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw 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 than late December.

Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, 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.

Atmospheric Ridge Sustains High Temperatures

Above-average warmth is expected to continue for the remainder of the week and beyond, with abnormal warmth projected to move across the southeastern US in the coming days.

The warmth has been fuelled by a powerful high-altitude ridge stretching from the southwestern deserts northward and eastward, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure over a large portion of North America, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.