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Northern Canada has been gripped by a bitter and extended period of frigid weather, with readings persisting from 20 to 40 degrees below zero for multiple weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in half a century.

Consecutive Nights Below -40C

In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row 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 a series of ten nights when temperatures dropped below -30C.

This Arctic air mass pushed further southward during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

Boxing Day was expected to bring readings no higher than -20 Celsius through a wide swath, from Edmonton in the west to Quebec in the east.

Forecast to Persist into the New Year

The frigid conditions are predicted to linger through the start of January. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the system endures record-high pressure from record-high energy demand.

The lengthy cold snap originates from the Arctic vortex settling over Canada for much of December, enabling a surge of icy Arctic winds to descend. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.

Stark Contrast with US Warmth

Conversely, sections of America recorded the hottest December 25th in their history as temperatures soared about 15-30C above the seasonal average. 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, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.

Atmospheric Ridge Sustains High Temperatures

Above-average warmth is expected to continue on December 26th and into the weekend, 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, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. Sinking atmospheric air undergoes compression and additional heating, allowing unusually warm temperatures to build.