We're ending April on a cool and wet note. Temperatures will average 15 degrees below average for highs for the last three days of the month. I did some checking on when that happened last and what happened the following May; here's what I found.
If the forecast holds true, the last three days of April this year in Sioux Falls will average 50 degrees. Since 1990, I found three instances when the average high for the last three days of the month was 50 degrees or less.
In 2005, the average high for April 28 through 30 was 50 degrees. That following May gave Sioux Falls slightly below average highs in May with well above average rain.
The next instance was in 1994 with an average high of 42. That following May was much different; it was very warm with an average high of 77 and very dry with well below average rain.
1990 went back to cool and wet weather with slightly below average highs and above average rain.