In late December, many Americans reached for cold-weather gear as a blast of unusually cold Arctic air poured south and fueled a travel nightmare around Christmas. In the first few days of January 2023, conditions changed dramatically. Instead of unseasonable cold, many of the same areas experienced unusual warmth. With temperatures running 20-30 degrees Fahrenheit higher than normal in the eastern U.S., spring-like weather broke temperature records in several states.
This animation shows surface air temperature across part of the Northern Hemisphere, including North America, for December 2022 and the first few days of January 2023. The darkest reds show areas with the warmest surface temperatures; blue areas show areas with the lowest surface temperatures. The short pulses reflect daily daytime warming and nighttime cooling, but the spread of cold Arctic air south over much of the U.S. became apparent toward the end of the month, especially in the week before Christmas.