An mass of cold Arctic air has descended from the north over the continent, causing temperatures to plunge across Canada and the eastern half of the United States. Many regions between Nunavut and Ontario are seeing temperatures well below zero — Fahrenheit, that is (-32ºC), cold enough to crack windows in Alberta and Saskatchewan. Although low-temperature records in many regions aren’t being broken, these conditions are encroaching on century-old records for the duration of regional cold snaps.
"How cold is it?" To put this cold snap in perspective, the temperature at Base Camp at the foot of Mount Everest was -35ºC (-31ºF) on Thursday, on-par with the -36ºC (-32.8ºF) experienced by Canada’s cities of Yellowknife and Churchill. Amundsen-Scott Weather Station in Antarctica was a balmy -16ºC (3.2ºF), although the southern hemisphere is currently experiencing austral summer. But the real kicker might be that the daily high for Mars’ Gale Crater was -23ºC (-9.4ºF) on Thursday — a similar temperature experienced by many Earth-bound cities across North America.
The cause of the continent’s deep freeze is a combination of factors, beginning with the jet stream bulging up from the Pacific Ocean over Alaska, causing record warmth for this time of year in the state. This bulge has prompted a gyre further east to bring cold air down over Hudson Bay, pushing Arctic conditions down well into the US southeast.
Cities such as Chicago, Detroit, New York, and Boston are reporting daily highs that only reach the low teens or single digits, and because of the slow-to-shift nature of the jet stream’s patterns, this cold spell is expected to drag on until at least January 10. Ottawa, Canada’s capital city, has cancelled official New Year’s Eve celebration plans due to the extreme cold, forecast to dip to -24ºC (-11.2ºF) in the final, frigid moments of 2017.