Weather history and climate summary information is available for the following locations:
- Des Moines
- Sioux City
Warmest May Days
The warmest May days in Iowa are:
| Sioux City, Iowa | 2001 | 100.9°F |
| Sioux City, Iowa | 2006 | 98.1°F |
| Sioux City, Iowa | 2009 | 97°F |
| Sioux City, Iowa | 1943 | 96.3°F |
| Sioux City, Iowa | 2011 | 96.1°F |
Coldest May Days
The coldest May days in Iowa were:
| Sioux City, Iowa | 1976 | 25°F |
| Sioux City, Iowa | 2011 | 26.1°F |
| Des Moines, Iowa | 1975 | 26.1°F |
| Sioux City, Iowa | 1997 | 26.1°F |
| Sioux City, Iowa | 2005 | 27°F |
Wettest May Days
The wettest single days in May occurred:
| Des Moines, Iowa | 1973 | 12.6 inches |
| Sioux City, Iowa | 1973 | 5.9 inches |
| Des Moines, Iowa | 1996 | 3.1 inches |
| Des Moines, Iowa | 2010 | 2.4 inches |
| Des Moines, Iowa | 2005 | 2.4 inches |