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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with readings persisting in the minus 20 to minus 40 Celsius range for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature since 1975.

Enduring Chill in the Deep Minus Forties

Meanwhile, Mayo and Dawson endured over two straight weeks of nights below -40C, with Mayo plunging to -50.4C at the start of the week. Whitehorse also recorded a series of ten nights when the cold dipped under -30 Celsius.

This Arctic air mass pushed further southward over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

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 for the foreseeable future. Officials have warned that the Yukon could face electricity outages soon, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.

The lengthy cold snap originates from the polar vortex remaining anchored over Canada for much of December, enabling a surge of icy Arctic winds to descend. 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.

Pronounced Disparity to American Heat

In stark contrast, parts of the US experienced their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

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. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

High-Pressure System Drives the Heat

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with atypical high temperatures expected to spread across the southeastern US in the coming days.

This heat is being driven by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure across much of the continent, which holds warm air close to the ground. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.