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An intense cold spell has seized a severe and lengthy Arctic outbreak, with readings persisting from 20 to 40 degrees below zero for multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature in nearly five decades.

Enduring Chill Below -40C

Meanwhile, Mayo and Dawson endured 16 consecutive nights colder than minus 40 degrees, with Mayo experiencing a low of -50.4C earlier this week. The capital, Whitehorse, likewise saw a series of ten nights when the cold dipped under -30 Celsius.

The deep freeze spread farther south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

Boxing Day was expected to bring minimum temperatures of at least minus 20C in numerous areas, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist Through Early January

The frigid conditions are predicted to linger through the start of January. There are warnings of possible electrical grid strain in Yukon territory soon, as its energy infrastructure faces unprecedented demand from record-high energy demand.

This extended freeze is the result of the Arctic vortex settling over Canada for much of December, enabling a surge of icy Arctic winds to descend. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.

Stark Contrast Compared to Stateside Temperatures

Conversely, sections of America recorded historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. Across wide regions, the atmosphere was more akin to late spring 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. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

Heat-Dome Effect Fuels Warmth

Above-average warmth is expected to continue for the remainder of the week and beyond, with atypical high temperatures expected to spread into the south-eastern states later in the week.

The unseasonable temperatures are powered by a powerful high-altitude ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This pattern establishes a broad area of high pressure 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.