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The temperatures in Helena in September are quite cold with temperatures between 6°C and 21°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Helena during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Please note that Helena can expect a few days of snow in September.
Our weather forecast can give you a great sense of what weather to expect in Helena in September 2025.
If you’re planning to visit Helena in the near future, we highly recommend that you review the 14 day weather forecast for Helena before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -2° / -9° | 6 | 10 | 16 | 39 mm | Awful | Helena in January |
| February | -2° / -10° | 6 | 5 | 18 | 47 mm | Awful | Helena in February |
| March | 4° / -5° | 8 | 10 | 15 | 62 mm | Awful | Helena in March |
| April | 9° / -3° | 8 | 10 | 12 | 86 mm | Awful | Helena in April |
| May | 15° / 2° | 9 | 19 | 3 | 106 mm | Bad | Helena in May |
| June | 21° / 6° | 8 | 22 | 0 | 105 mm | Ok | Helena in June |
| July | 28° / 9° | 3 | 28 | 0 | 45 mm | Perfect | Helena in July |
| August | 26° / 10° | 3 | 28 | 0 | 49 mm | Perfect | Helena in August |
| September | 21° / 6° | 3 | 26 | 1 | 44 mm | Good | Helena in September |
| October | 11° / 0° | 4 | 22 | 6 | 51 mm | Bad | Helena in October |
| November | 3° / -6° | 3 | 15 | 12 | 38 mm | Awful | Helena in November |
| December | -3° / -10° | 6 | 8 | 17 | 37 mm | Awful | Helena in December |