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An intense cold spell has seized an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in half a century.

Prolonged Freeze Below -40C

Meanwhile, Mayo and Dawson endured 16 consecutive nights dipping under the minus 40 Celsius threshold, with Mayo experiencing a low of -50.4C at the start of the week. Whitehorse similarly reported ten separate nights when the cold dipped under -30 Celsius.

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

The day after Christmas was forecast to deliver readings no higher than -20 Celsius through a wide swath, encompassing cities from Edmonton to Quebec.

Expected to Continue into the New Year

The frigid conditions are predicted to linger through the start of January. Authorities have cautioned about potential power failures in the Yukon soon, as the territory’s power grid comes under strain from historically high electricity consumption.

The prolonged chill has been caused by the Arctic vortex settling over Canada for much of December, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.

Stark Contrast Compared to Stateside Temperatures

In stark contrast, parts of the US experienced 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 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, surpassing the previous peak of 22C set in 1982. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

Atmospheric Ridge Drives the Heat

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.

The unseasonable temperatures are powered by a powerful high-altitude 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 across much of the continent, which holds warm air close to the ground. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.