Here is what South Dakota looks like in the winter:

ice
USFWS

And here is what it looks like in the summer:

green

And over the weekend, the state basically switched from one to the other overnight. One day, the temperature was 22 degrees F. The next day, it was 92.

Ex-Grister Philip Bump writes at the Atlantic Wire:

While the increase in Aberdeen is unusual, it’s not the biggest 24-hour swing in history. That occurred in Montana in 1972, after the temperature went up 103 degrees overnight. The record for the largest increase in two minutes brings us back to South Dakota. On January 22, 1943, the temperature at 7:30 a.m. was -4. At 7:32, it was 45.

Moral of the story: Always wear a bathing suit under your North Face. Just in case.