What is the largest temperature swing ever to occur in the United States in just a few minutes?
It occurred at Spearfish, S. Dak., at 7:30 on the morning of Jan. 22, 1943. The temperature was a frigid 4 degrees below zero, but within two minutes, at 7:32am, the reading had shot up to 45 degrees above zero — a breath-taking increase of 49 degrees in just two minutes! The temperature continued climbing, albeit much more slowly, to 54 degree by 9am. But then the reading crashed and at 9:27am the thermometer again stood at 4 below zero, a drop of 58 degrees.
Spearfish is located in extreme western South Dakota. On that January day, cold arctic air was sloshed up into Spearfish and areas eastward, but the frigid air was very shallow. The arctic air, overlain by mild Pacific air, temporarily retreated eastward, allowing readings to surge, then it returned.