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A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with temperatures hovering from 20 to 40 degrees below zero for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in half a century.

Enduring Chill in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row colder than minus 40 degrees, with Mayo plunging to -50.4C on Monday. Whitehorse also recorded ten separate nights when the cold dipped under -30 Celsius.

The deep freeze spread farther south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.

The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, encompassing cities from Edmonton to Quebec.

Expected to Continue into the New Year

This harsh winter weather is expected to continue through the start of January. Authorities have cautioned about potential power failures in the Yukon over the next several days, as the system endures record-high pressure from peak power usage levels.

The lengthy cold snap originates from the polar vortex remaining anchored over Canada for much of December, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.

Stark Contrast with US Warmth

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 instead of the heart of winter.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.

High-Pressure System Drives the Heat

Above-average warmth is expected to continue for the remainder of the week and beyond, with unseasonable heat forecast to sweep into the south-eastern states later in the week.

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 over a large portion of North America, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, allowing unusually warm temperatures to build.