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Northern Canada has been gripped by an intense and prolonged cold spell, with temperatures hovering between -20C and -40C for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in half a century.

Consecutive Nights of Extreme Cold

Meanwhile, Mayo and Dawson endured 16 consecutive nights below -40C, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported ten separate nights when readings fell to minus 30 degrees or lower.

The deep freeze spread farther south through Christmas week. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

The day after Christmas was forecast to deliver 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

The frigid conditions are predicted to linger into the new year. Officials have warned that the Yukon could face electricity outages over the next several days, as the territory’s power grid comes under strain from historically high electricity consumption.

The prolonged chill has been caused by a stationary polar vortex over Canada for much of December, enabling a surge of icy Arctic winds to descend. Next week, the cold air mass is expected to retreat north allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Stark Contrast Compared to Stateside Temperatures

Conversely, sections of America recorded their warmest Christmas Day on record 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. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

Heat-Dome Effect Drives the Heat

Above-average warmth is expected to continue for the remainder of the week and beyond, with abnormal warmth projected to move across the southeastern US in the coming days.

The warmth has been fuelled 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, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.