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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with readings persisting from 20 to 40 degrees below zero for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in half a century.

Prolonged Freeze in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through 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 at the start of the week. Whitehorse similarly reported 10 nights when temperatures dropped below -30C.

The deep freeze spread farther south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in readings no higher than -20 Celsius across many regions, from Edmonton in the west to Quebec in the east.

Forecast to Persist 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 over the next several days, as the system endures record-high pressure from record-high energy demand.

This extended freeze is the result of the Arctic vortex settling above Canadian territory through December, enabling a surge of icy Arctic winds to descend. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Stark Contrast with US Warmth

In stark contrast, parts of the US experienced historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. In many areas, conditions felt more typical of April or May rather than the end of December.

A number of states broke historical records for December 25th warmth. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, surpassing the previous peak of 22C set in 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

Heat-Dome Effect Sustains High Temperatures

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 reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.