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A prolonged deep freeze has enveloped a bitter and extended period of frigid weather, with thermometers lingering in the minus 20 to minus 40 Celsius range for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in nearly five decades.

Consecutive Nights in the Deep Minus Forties

Meanwhile, Mayo and Dawson endured 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 10 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.

December 26th was anticipated to usher in minimum temperatures of at least minus 20C through a wide swath, encompassing cities from Edmonton to Quebec.

Likely to Linger into the New Year

The severe cold is forecast to persist through the start of January. There are warnings of possible electrical grid strain in Yukon territory in the coming days, as its energy infrastructure faces unprecedented demand from peak power usage levels.

The lengthy cold snap originates from the polar vortex remaining anchored 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.

Dramatic Difference Compared to Stateside Temperatures

In stark contrast, parts of the US experienced their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. For numerous locations, the weather resembled a spring day in April or May than late December.

A number of states broke historical records for December 25th warmth. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, 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.

Heat-Dome Effect Fuels Warmth

Above-average warmth is expected to continue through Boxing Day and the days ahead, with atypical high temperatures expected to spread 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 pattern establishes a broad area of high pressure across much of the continent, trapping warm air near the surface. Sinking atmospheric air undergoes compression and additional heating, allowing unusually warm temperatures to build.