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An intense cold spell has seized a bitter and extended period of frigid weather, with temperatures hovering from 20 to 40 degrees below zero for multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day in nearly five decades.

Enduring Chill Below -40C

Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. The capital, Whitehorse, likewise saw ten separate nights when readings fell to minus 30 degrees or lower.

The bitter chill extended its reach south over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist For Days to Come

The severe cold is forecast to persist through the start of January. There are warnings of possible electrical grid strain in Yukon territory in the coming days, as the system endures record-high pressure from record-high energy demand.

This extended freeze is the result of the Arctic vortex settling 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 slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.

Pronounced Disparity Compared to Stateside Temperatures

Conversely, sections of America recorded their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. In many areas, conditions felt more typical of April or May rather than the end of December.

Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, exceeding the old record of 22C from 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

Atmospheric Ridge Drives the Heat

Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with abnormal warmth projected to move through the American Southeast soon.

The warmth has been fuelled by a powerful high-altitude ridge extending from the desert south-west towards the north and east, creating a heat-dome effect. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. Sinking atmospheric air undergoes compression and additional heating, allowing unusually warm temperatures to build.