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Northern Canada has been gripped by an intense and prolonged cold spell, with temperatures hovering in the minus 20 to minus 40 Celsius range for multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading in half a century.

Consecutive Nights of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. 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.

The day after Christmas was forecast to deliver minimum temperatures of at least minus 20C across many regions, from Edmonton in the west to Quebec in the east.

Forecast to Persist For Days to Come

The severe cold is forecast to persist for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the territory’s power grid comes under strain from peak power usage levels.

The prolonged chill has been caused by the polar vortex remaining anchored above Canadian territory through December, allowing bitter Arctic air to spill south. In the coming week, forecasts indicate this cold air will pull back northward slowly, permitting warmer Pacific winds to flow over America and reach into portions of southern Canada.

Pronounced Disparity Compared to Stateside Temperatures

Conversely, sections of America recorded the hottest December 25th in their history as the mercury climbed roughly 15 to 30 degrees above typical averages. In many areas, conditions felt more typical of April or May than late December.

Several states set Christmas Day temperature records. 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.

High-Pressure System Sustains High Temperatures

Above-average warmth is expected to continue through Boxing Day and the days ahead, with unseasonable heat forecast to sweep into the south-eastern states later in the week.

This heat is being driven by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure across much of the continent, which holds warm air close to the ground. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.