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Northern Canada has been gripped by a severe and lengthy Arctic outbreak, with temperatures hovering in the minus 20 to minus 40 Celsius range for weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, marking its chilliest December reading since 1975.

Enduring Chill Below -40C

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.

This Arctic air mass pushed further southward during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

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

Likely to Linger For Days to Come

The severe cold is forecast to persist through the start of January. Officials have warned that the Yukon could face electricity outages in the coming days, as the system endures record-high pressure from historically high electricity consumption.

The prolonged chill has been caused by a stationary polar vortex across the northern part of the continent this month, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Stark Contrast to American Heat

Conversely, sections of America recorded their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. For numerous locations, the weather resembled a spring day in April or May rather than the end of December.

A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, exceeding the old record of 22C from 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.

Atmospheric Ridge Fuels Warmth

Above-average warmth is expected to continue on December 26th and into the weekend, with abnormal warmth projected to move across the southeastern US in the coming days.

This heat is being driven by a robust atmospheric ridge reaching from the arid southwest across the continent, 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. Sinking atmospheric air undergoes compression and additional heating, fostering the buildup of exceptional warmth.