🔗 Share this article Arctic Blast Tightens Hold on the Great White North as America Sees Warmest Christmas in History. 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 multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading since 1975. Consecutive Nights in the Deep Minus Forties Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights below -40C, with Mayo experiencing a low of -50.4C at the start of the week. Whitehorse also recorded a series of ten nights when temperatures dropped below -30C. This Arctic air mass pushed further southward during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C. The day after Christmas was forecast to deliver readings no higher than -20 Celsius through a wide swath, including Edmonton, Montreal, Ottawa and Quebec. Expected to Continue into the New Year The severe cold is forecast to persist into the new year. Officials have warned that the Yukon could face electricity outages in the coming days, as the territory’s power grid comes under strain from record-high energy demand. The lengthy cold snap originates from the polar vortex remaining anchored across the northern part of the continent this month, which funnels frigid northern air southward. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across the US and into parts 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. For numerous locations, the weather resembled a spring day in April or May rather than the end of December. Multiple states established new Christmas temperature highs. The capital of Oklahoma soared to 25C on Christmas Day, surpassing the previous peak of 22C set in 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius. Heat-Dome Effect Drives the Heat Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with atypical high temperatures expected to spread through the American Southeast soon. The unseasonable temperatures are powered by a robust atmospheric ridge extending from the desert south-west towards the north and east, which generates a heat-dome phenomenon. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, trapping warm air near the surface. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.