Weather history and climate summary information is available for the following locations:
- Boise
- Mountain Home
- Pocatello
Warmest September Days
The warmest September days in Idaho are:
| Mountain Home, Idaho | 1955 | 104°F |
| Mountain Home, Idaho | 1945 | 102.4°F |
| Mountain Home, Idaho | 2007 | 102.2°F |
| Mountain Home, Idaho | 1987 | 100.9°F |
| Boise, Idaho | 2007 | 100.9°F |
Coldest September Days
The coldest September days in Idaho were:
| Pocatello, Idaho | 1985 | 19°F |
| Pocatello, Idaho | 1983 | 19°F |
| Pocatello, Idaho | 1999 | 21.9°F |
| Pocatello, Idaho | 2000 | 21.9°F |
| Mountain Home, Idaho | 1965 | 24.1°F |
Wettest September Days
The wettest single days in September occurred:
| Boise, Idaho | 1976 | 1.7 inches |
| Pocatello, Idaho | 2000 | 1.2 inches |
| Mountain Home, Idaho | 1980 | 1.1 inches |
| Pocatello, Idaho | 1983 | 1 inches |
| Pocatello, Idaho | 1982 | 0.9 inches |