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Northern Canada has been gripped by an intense and prolonged cold spell, with readings persisting between -20C and -40C for multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature since 1975.

Consecutive Nights of Extreme Cold

Meanwhile, Mayo and Dawson endured sixteen nights in a row below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. Whitehorse also recorded 10 nights when temperatures dropped below -30C.

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 minimum temperatures of at least minus 20C in numerous areas, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist Through Early January

The severe cold is forecast to persist into the new year. Officials have warned that the Yukon could face electricity outages in the coming days, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.

This extended freeze is the result of a stationary polar vortex across the northern part of the continent this month, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over the US and into parts of southern Canada.

Stark Contrast to American Heat

In stark contrast, parts of the US experienced their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

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. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

Heat-Dome Effect Drives the Heat

Unseasonable heat is predicted to persist for the remainder of the week and beyond, with atypical high temperatures expected to spread 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, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.