Weather history and climate summary information is available for the following locations:
- Huron
- Rapid City
- Sioux Falls
- Watertown
Warmest September Days
The warmest September days in South Dakota are:
| Huron, South Dakota | 1983 | 104°F |
| Huron, South Dakota | 1976 | 104°F |
| Sioux Falls, South Dakota | 1976 | 104°F |
| Huron, South Dakota | 1978 | 104°F |
| Rapid City, South Dakota | 1960 | 102.9°F |
Coldest September Days
The coldest September days in South Dakota were:
| Huron, South Dakota | 1974 | 19°F |
| Rapid City, South Dakota | 1942 | 19.4°F |
| Sioux Falls, South Dakota | 1974 | 21.9°F |
| Watertown, South Dakota | 1984 | 23°F |
| Sioux Falls, South Dakota | 1984 | 23°F |
Wettest September Days
The wettest single days in September occurred:
| Watertown, South Dakota | 2006 | 3.2 inches |
| Sioux Falls, South Dakota | 1982 | 2.7 inches |
| Sioux Falls, South Dakota | 1977 | 2.6 inches |
| Huron, South Dakota | 2008 | 2.5 inches |
| Sioux Falls, South Dakota | 1986 | 2.5 inches |