Click on a day for an hourly weather forecast
The temperatures in Yellowstone in September are comfortable with low of 16°C and and high up to 26°C.
You can expect about 3 to 8 days of rain in Yellowstone 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.
Our weather forecast can give you a great sense of what weather to expect in Yellowstone in September 2025.
If you’re planning to visit Yellowstone in the near future, we highly recommend that you review the 14 day weather forecast for Yellowstone before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 3° / -4° | 8 | 20 | 3 | 86 mm | Awful | Yellowstone in January |
| February | 6° / -3° | 8 | 17 | 4 | 104 mm | Awful | Yellowstone in February |
| March | 12° / 3° | 8 | 22 | 1 | 125 mm | Bad | Yellowstone in March |
| April | 18° / 7° | 9 | 21 | 0 | 151 mm | Ok | Yellowstone in April |
| May | 23° / 13° | 10 | 21 | 0 | 132 mm | Good | Yellowstone in May |
| June | 28° / 18° | 10 | 20 | 0 | 118 mm | Good | Yellowstone in June |
| July | 30° / 20° | 10 | 21 | 0 | 108 mm | Ok | Yellowstone in July |
| August | 29° / 19° | 8 | 23 | 0 | 80 mm | Ok | Yellowstone in August |
| September | 26° / 16° | 6 | 24 | 0 | 73 mm | Perfect | Yellowstone in September |
| October | 19° / 9° | 6 | 25 | 0 | 94 mm | Good | Yellowstone in October |
| November | 11° / 3° | 6 | 23 | 1 | 90 mm | Ok | Yellowstone in November |
| December | 6° / -1° | 8 | 21 | 2 | 103 mm | Awful | Yellowstone in December |