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A prolonged deep freeze has enveloped a bitter and extended period of frigid weather, 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, its coldest December temperature in half a century.

Enduring Chill of Extreme Cold

Meanwhile, Mayo and Dawson endured sixteen nights in a row colder than minus 40 degrees, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported 10 nights when the cold dipped under -30 Celsius.

This Arctic air mass pushed further southward during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

Boxing Day was expected to bring lows of at least -20C across many regions, encompassing cities from Edmonton to Quebec.

Forecast to Persist into the New Year

This harsh winter weather is expected to continue into the new year. Officials have warned that the Yukon could face electricity outages soon, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.

This extended freeze is the result of the polar vortex remaining anchored across the northern part of the continent this month, allowing bitter Arctic air to spill south. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.

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.

Multiple states established new Christmas temperature highs. The capital of Oklahoma soared to 25C on Christmas Day, exceeding the old record of 22C from 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

Atmospheric Ridge Fuels Warmth

Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with atypical high temperatures expected to spread across the southeastern US in the coming days.

The warmth has been fuelled by a robust atmospheric ridge extending from the desert south-west towards the north and east, creating a heat-dome effect. Such a configuration results in a widespread high-pressure system over a large portion of North America, which holds warm air close to the ground. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.