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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with temperatures hovering in the minus 20 to minus 40 Celsius range for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in nearly five decades.

Prolonged Freeze in the Deep Minus Forties

Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row colder than minus 40 degrees, with Mayo experiencing a low of -50.4C at the start of the week. The capital, Whitehorse, likewise saw ten separate nights when readings fell to minus 30 degrees or lower.

The bitter chill extended its reach south through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.

December 26th was anticipated to usher in readings no higher than -20 Celsius in numerous areas, including Edmonton, Montreal, Ottawa and Quebec.

Forecast to Persist into the New Year

This harsh winter weather is expected to continue for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon over the next several days, as its energy infrastructure faces unprecedented demand from record-high energy demand.

The lengthy cold snap originates from the Arctic vortex settling over Canada for much of December, allowing bitter Arctic air to spill south. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.

Pronounced Disparity with US Warmth

Meanwhile, in a dramatic contrast, areas of the United States saw historically high temperatures for Christmas as readings skyrocketed 15 to 30 degrees Celsius above normal. In many areas, conditions felt more typical of April or May rather than the end of December.

Several states set Christmas Day temperature records. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

Heat-Dome Effect Sustains High Temperatures

Above-average warmth is expected to continue through Boxing Day and the days ahead, with atypical high temperatures expected to spread into the south-eastern states later in the week.

This heat is being driven by a strong upper-level ridge reaching from the arid southwest across the continent, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.