Temperatures across much of China rose above freezing for the first time in weeks Sunday, capping the most severe cold snap in the country in seven decades. Thermometers in Beijing had remained below 0 degrees Celsius since Dec. 11, with some parts of northeastern China reaching minus 40 degrees (in both Celsius and Fahrenheit; see here).
Researchers say the culprit may be a weakened polar vortex—a wobbling in the jet stream that circles the Arctic, see illustration here—which allows frigid air masses to dip down from the Earth's northern pole. A similar phenomenon was responsible for severe winter weather in 2021, which dipped as far south as Texas, leaving almost 250 people dead.
The freezing temperatures are the latest in a series of extreme weather events for the region. Record temperatures were set in Beijing for 27 consecutive days this summer, while the northeast saw its heaviest rainfall in 140 years.