Weather history and climate summary information is available for the following locations:
- Billings
- Glasgow
- Great Falls
- Helena
- Lewistown
- Miles City
- Missoula
Warmest October Days
The warmest October days in Montana are:
| Miles City, Montana | 2011 | 95°F |
| Miles City, Montana | 1997 | 93.2°F |
| Miles City, Montana | 2005 | 93°F |
| Miles City, Montana | 1992 | 91.9°F |
| Billings, Montana | 2011 | 91°F |
Coldest October Days
The coldest October days in Montana were:
| Helena, Montana | 1991 | -8°F |
| Lewistown, Montana | 2002 | -8°F |
| Great Falls, Montana | 1991 | -8°F |
| Miles City, Montana | 1991 | -7.8°F |
| Lewistown, Montana | 1991 | -7.8°F |
Wettest October Days
The wettest single days in October occurred:
| Helena, Montana | 1987 | 3.5 inches |
| Billings, Montana | 1974 | 2 inches |
| Billings, Montana | 1994 | 1.4 inches |
| Billings, Montana | 1993 | 1.4 inches |
| Glasgow, Montana | 1998 | 1.4 inches |