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A prolonged deep freeze has enveloped an intense and prolonged cold spell, 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, representing its most frigid December day since 1975.

Consecutive Nights in the Deep Minus Forties

In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C at the start of the week. Whitehorse similarly reported a series of ten 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.

Boxing Day was expected to bring readings no higher than -20 Celsius in numerous areas, encompassing cities from Edmonton to Quebec.

Forecast to Persist into the New Year

The severe cold is forecast to persist into the new year. Authorities have cautioned about potential power failures in the Yukon soon, as the territory’s power grid comes under strain 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 US and into parts of southern Canada.

Stark Contrast to American Heat

In stark contrast, parts of the US experienced the hottest December 25th in their history 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 than late December.

Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.

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.

This heat is being driven by a strong upper-level ridge reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. Such a configuration results in a widespread high-pressure system over a large portion of North America, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, allowing unusually warm temperatures to build.