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An intense cold spell has seized a bitter and extended period of frigid weather, with thermometers lingering 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 in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row colder than minus 40 degrees, with Mayo experiencing a low of -50.4C at the start of the week. Whitehorse also recorded ten separate nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.

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

Likely to Linger Through Early January

This harsh winter weather is expected to continue for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory soon, as the territory’s power grid comes under strain from peak power usage levels.

The lengthy cold snap originates from the polar vortex remaining anchored across the northern part of the continent this month, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across America and reach into portions of southern Canada.

Pronounced Disparity with US Warmth

In stark contrast, parts of the US experienced their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. In many areas, conditions felt more typical of April or May rather than the end of 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. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

Heat-Dome Effect Sustains High Temperatures

Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with unseasonable heat forecast to sweep through the American Southeast soon.

This heat is being driven by a strong upper-level 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, effectively capping warm air at lower altitudes. As air sinks through the atmosphere, it compresses and heats further, allowing unusually warm temperatures to build.