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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. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in half a century.

Prolonged Freeze of Extreme Cold

Meanwhile, Mayo and Dawson endured sixteen nights in a row colder than minus 40 degrees, with Mayo plunging to -50.4C on Monday. Whitehorse similarly reported ten separate nights when readings fell to minus 30 degrees or lower.

This Arctic air mass pushed further southward during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C in numerous areas, from Edmonton in the west to Quebec in the east.

Likely to Linger Through Early January

This harsh winter weather is expected to continue into the new year. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the territory’s power grid comes under strain from peak power usage levels.

The lengthy cold snap originates from a stationary polar vortex above Canadian territory through December, allowing bitter Arctic air to spill south. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across the United States and penetrate southern Canadian regions.

Stark Contrast Compared to Stateside Temperatures

Meanwhile, in a dramatic contrast, areas of the United States saw their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. For numerous locations, the weather resembled a spring day in April or May rather than the end of December.

A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, topping the prior high mark of 22 degrees established over forty years ago. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Drives the Heat

Above-average warmth is expected to continue on December 26th and into the weekend, with atypical high temperatures expected to spread across the southeastern US in the coming days.

The warmth has been fuelled by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. Such a configuration results in a widespread high-pressure system over a large portion of North America, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.