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Northern Canada has been gripped by an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for 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 sixteen nights in a row below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. Whitehorse also recorded a series of ten nights when the cold dipped under -30 Celsius.

This Arctic air mass pushed further southward through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in lows of at least -20C in numerous areas, encompassing cities from Edmonton to Quebec.

Expected to Continue For Days to Come

This harsh winter weather is expected to continue into the new year. There are warnings of possible electrical grid strain in Yukon territory soon, as the territory’s power grid comes under strain from peak power usage levels.

The prolonged chill has been caused by the Arctic vortex settling over Canada for much of 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 America and reach into portions of southern Canada.

Stark Contrast with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw the hottest December 25th in their history as temperatures soared about 15-30C above the seasonal average. For numerous locations, the weather resembled a spring day in April or May than late December.

Multiple states established new Christmas temperature highs. 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 similarly saw thermometers rise past the 25C mark.

Heat-Dome Effect Drives the Heat

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with abnormal warmth projected to move across the southeastern US in the coming days.

The unseasonable temperatures are powered by a strong upper-level ridge reaching from the arid southwest across the continent, creating a heat-dome effect. Such a configuration results in a widespread high-pressure system blanketing a significant part of the landmass, trapping warm air near the surface. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.