🔗 Share this article

An intense cold spell has seized an intense and prolonged cold spell, with readings persisting between -20C and -40C for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in nearly five decades.

Consecutive Nights in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights colder than minus 40 degrees, with Mayo plunging to -50.4C at the start of the week. Whitehorse similarly reported 10 nights when the cold dipped under -30 Celsius.

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 lows of at least -20C through a wide swath, encompassing cities from Edmonton to Quebec.

Forecast to Persist For Days to Come

The severe cold is forecast to persist for the foreseeable future. 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 prolonged chill has been caused by the polar vortex remaining anchored over Canada for much of December, allowing bitter Arctic air to spill south. 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.

Dramatic Difference to American Heat

In stark contrast, parts of the US experienced 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 than late December.

A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, 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

Unseasonable heat is predicted to persist for the remainder of the week and beyond, with atypical high temperatures expected to spread through the American Southeast soon.

This heat is being driven by a powerful high-altitude ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, which holds warm air close to the ground. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.