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An intense cold spell has seized a severe and lengthy Arctic outbreak, with thermometers lingering between -20C and -40C for weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, marking its chilliest December reading in nearly five decades.

Prolonged Freeze of Extreme Cold

In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse also recorded ten separate nights when temperatures dropped below -30C.

The bitter chill extended its reach south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

The day after Christmas was forecast to deliver lows of at least -20C in numerous areas, encompassing cities from Edmonton to Quebec.

Likely to Linger into the New Year

This harsh winter weather is expected to continue through the start of January. Authorities have cautioned about potential power failures in the Yukon soon, as the system endures record-high pressure from historically high electricity consumption.

The lengthy cold snap originates from the Arctic vortex settling 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 gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Dramatic Difference with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw the hottest December 25th in their history as readings skyrocketed 15 to 30 degrees Celsius above normal. In many areas, conditions felt more typical of April or May than late December.

A number of states broke historical records for December 25th warmth. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

High-Pressure System Fuels Warmth

Above-average warmth is expected to continue through Boxing Day and the days ahead, with atypical high temperatures expected to spread across the southeastern US in the coming days.

This heat is being driven by a powerful high-altitude 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, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, allowing unusually warm temperatures to build.