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Northern Canada has been gripped by a bitter and extended period of frigid weather, with temperatures hovering between -20C and -40C for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in half a century.

Prolonged Freeze of Extreme Cold

In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. Whitehorse similarly reported a series of ten nights when the cold dipped under -30 Celsius.

The bitter chill extended its reach south during the holiday season. 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.

Likely to Linger into the New Year

The severe cold is forecast to persist into the new year. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the system endures record-high pressure from historically high electricity consumption.

This extended freeze is the result of a stationary polar vortex across the northern part of the continent this month, enabling a surge of icy Arctic winds to descend. In the coming week, forecasts indicate this cold air will pull back northward gradually, enabling milder Pacific air to move across America and reach into portions of southern Canada.

Dramatic Difference Compared to Stateside Temperatures

In stark contrast, parts of the US experienced historically high temperatures for Christmas as readings skyrocketed 15 to 30 degrees Celsius above normal. 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. 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 also logged readings above 25 degrees Celsius.

Heat-Dome Effect Sustains High Temperatures

Above-average warmth is expected to continue on December 26th and into the weekend, with atypical high temperatures expected to spread across the southeastern US in the coming days.

The warmth has been fuelled by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, creating a heat-dome effect. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.