It is cold in Colorado today, and I have the heat turned on. But May 20 wasn’t always a cold day. On this date in 1934, almost half of the US was over 90 degrees, and South Dakota and Nebraska were well over 100 degrees. It was 105 degrees at Gann Valley, SD.

The average temperature across the US was 85 degrees on May 20, 1934.  Over the past century, May 20 afternoon temperatures have plummeted in the US, with recent years being among the coldest.