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A prolonged deep freeze has enveloped a bitter and extended period of frigid weather, with readings persisting between -20C and -40C for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in half a century.

Prolonged Freeze in the Deep Minus Forties

Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights dipping under the minus 40 Celsius threshold, with Mayo experiencing a low of -50.4C on Monday. Whitehorse similarly reported a series of ten nights when temperatures dropped below -30C.

The deep freeze spread farther south through Christmas week. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.

Boxing Day was expected to bring minimum temperatures of at least minus 20C across many regions, from Edmonton in the west to Quebec in the east.

Expected to Continue For Days to Come

This harsh winter weather is expected to continue through the start of January. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the system endures record-high pressure from record-high energy demand.

This extended freeze is the result of a stationary polar vortex 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 America and reach into portions of southern Canada.

Pronounced Disparity with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. In many areas, conditions felt more typical of April or May instead of the heart of winter.

Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Urban centers like Austin, Dallas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Drives the Heat

Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with abnormal warmth projected to move across the southeastern US in the coming days.

This heat is being driven by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure across much of the continent, effectively capping warm air at lower altitudes. Sinking atmospheric air undergoes compression and additional heating, fostering the buildup of exceptional warmth.