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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with temperatures hovering 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 in nearly five decades.

Prolonged Freeze of Extreme Cold

In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. Whitehorse also recorded ten separate nights when readings fell to minus 30 degrees or lower.

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

The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, from Edmonton in the west to Quebec in the east.

Forecast to Persist Through Early January

The frigid conditions are predicted to linger through the start of January. Officials have warned that the Yukon could face electricity outages soon, as its energy infrastructure faces unprecedented demand from record-high energy demand.

The prolonged chill has been caused by the Arctic vortex settling above Canadian territory through December, enabling a surge of icy Arctic winds to descend. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Stark Contrast to American Heat

In stark contrast, parts of the US experienced the hottest December 25th in their history as the mercury climbed roughly 15 to 30 degrees above typical averages. For numerous locations, the weather resembled a spring day in April or May instead of the heart of winter.

A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, exceeding the old record of 22C from 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

Above-average warmth is expected to continue for the remainder of the week and beyond, with atypical high temperatures expected to spread through the American Southeast soon.

The unseasonable temperatures are powered by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.