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A prolonged deep freeze has enveloped an intense and prolonged cold spell, with temperatures hovering from 20 to 40 degrees below zero for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading since 1975.

Enduring Chill of Extreme Cold

Meanwhile, Mayo and Dawson endured sixteen nights in a row below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. The capital, Whitehorse, likewise saw a series of ten nights when temperatures dropped below -30C.

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 through a wide swath, encompassing cities from Edmonton to Quebec.

Forecast to Persist For Days to Come

This harsh winter weather is expected to continue into the new year. Authorities have cautioned about potential power failures in the Yukon over the next several days, as the system endures record-high pressure from historically high electricity consumption.

The prolonged chill has been caused by the Arctic vortex settling over Canada for much of December, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north slowly, permitting warmer Pacific winds to flow over the US and into parts of southern Canada.

Pronounced Disparity Compared to Stateside Temperatures

In stark contrast, parts of the US experienced the hottest December 25th in their history as the mercury climbed roughly 15 to 30 degrees above typical averages. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

Multiple states established new Christmas temperature highs. The capital of Oklahoma soared to 25C on Christmas Day, surpassing the previous peak of 22C set in 1982. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.

Heat-Dome Effect Drives the Heat

Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with abnormal warmth projected to move into the south-eastern states later in the week.

The warmth has been fuelled by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure across much of the continent, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, fostering the buildup of exceptional warmth.