Click on a day for an hourly weather forecast
The temperatures in Montana in September are comfortable with low of 10°C and and high up to 24°C.
The wather in Montana in September can vary between cold and nice weather days. Expect a few rainy days but usually not more than 3.
Our weather forecast can give you a great sense of what weather to expect in Montana in September 2025.
If you’re planning to visit Montana in the near future, we highly recommend that you review the 14 day weather forecast for Montana before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 0° / -8° | 4 | 13 | 14 | 31 mm | Awful | Montana in January |
| February | 0° / -9° | 4 | 10 | 15 | 37 mm | Awful | Montana in February |
| March | 8° / -3° | 5 | 15 | 11 | 51 mm | Bad | Montana in March |
| April | 12° / 1° | 6 | 17 | 7 | 74 mm | Bad | Montana in April |
| May | 18° / 6° | 8 | 22 | 1 | 92 mm | Ok | Montana in May |
| June | 25° / 10° | 5 | 25 | 0 | 62 mm | Perfect | Montana in June |
| July | 31° / 15° | 2 | 29 | 0 | 29 mm | Good | Montana in July |
| August | 29° / 15° | 2 | 29 | 0 | 42 mm | Good | Montana in August |
| September | 24° / 10° | 2 | 28 | 0 | 34 mm | Perfect | Montana in September |
| October | 14° / 3° | 3 | 24 | 4 | 57 mm | Ok | Montana in October |
| November | 7° / -3° | 4 | 18 | 8 | 31 mm | Bad | Montana in November |
| December | 0° / -8° | 5 | 11 | 14 | 28 mm | Awful | Montana in December |