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Northern Canada has been gripped by a bitter and extended period of frigid weather, with temperatures hovering in the minus 20 to minus 40 Celsius range for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature in nearly five decades.

Enduring Chill of Extreme Cold

Meanwhile, Mayo and Dawson endured sixteen nights in a row dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported a series of ten nights when readings fell to minus 30 degrees or lower.

The bitter chill extended its reach south during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

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

Likely to Linger into the New Year

The frigid conditions are predicted to linger into the new year. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as its energy infrastructure faces unprecedented demand from peak power usage levels.

The prolonged chill has been caused by the polar vortex remaining anchored across the northern part of the continent this month, 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 the US and into parts of southern Canada.

Pronounced Disparity to American Heat

In stark contrast, parts of the US experienced their warmest Christmas Day on record as the mercury climbed roughly 15 to 30 degrees above typical averages. For numerous locations, the weather resembled a spring day in April or May than late December.

A number of states broke historical records for December 25th warmth. 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 Fuels Warmth

Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with unseasonable heat forecast to sweep into the south-eastern states later in the week.

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