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An intense cold spell has seized an intense and prolonged cold spell, with readings persisting between -20C and -40C for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading in nearly five decades.

Consecutive Nights of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. Whitehorse also recorded ten separate nights when the cold dipped under -30 Celsius.

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

The day after Christmas was forecast to deliver lows of at least -20C across many regions, from Edmonton in the west to Quebec in the east.

Likely to Linger For Days to Come

This harsh winter weather is expected to continue for the foreseeable future. Officials have warned that the Yukon could face electricity outages over the next several days, as its energy infrastructure faces unprecedented demand from peak power usage levels.

The prolonged chill has been caused by a stationary polar vortex over Canada for much of December, which funnels frigid northern air southward. 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 historically high temperatures for Christmas as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring rather than the end of December.

A number of states broke historical records for December 25th warmth. In Oklahoma, Oklahoma City hit 25C on Tuesday, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.

High-Pressure System Sustains High Temperatures

Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with unseasonable heat forecast to sweep across the southeastern US in the coming days.

This heat is being driven by a robust atmospheric ridge reaching from the arid southwest across the continent, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure across much of the continent, trapping warm air near the surface. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.