Arctic Blast Envelops Canada as US Records Hottest Christmas Ever.

Northern Canada has been gripped by an intense and prolonged cold spell, with readings persisting from 20 to 40 degrees below zero for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, its coldest December temperature in half a century.

Consecutive Nights of Extreme Cold

Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. The capital, Whitehorse, likewise saw ten separate nights when readings fell to minus 30 degrees or lower.

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

The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.

Likely to Linger into the New Year

The severe cold is forecast to persist for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the territory’s power grid comes under strain from record-high energy demand.

The prolonged chill has been caused by the polar vortex remaining anchored over Canada for much of December, enabling a surge of icy Arctic winds to descend. Next week, the cold air mass is expected to retreat north gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.

Dramatic Difference to American Heat

Conversely, sections of America recorded their warmest Christmas Day on record as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring than late December.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Drives the Heat

Above-average warmth is expected to continue on December 26th and into the weekend, with atypical high temperatures expected to spread into the south-eastern states later in the week.

The unseasonable temperatures are powered by a strong upper-level ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure over a large portion of North America, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.