Click on a day for an hourly weather forecast
The temperatures in Rapid City in August are comfortable with low of 17°C and and high up to 29°C.
You can expect about 3 to 8 days of rain in Rapid City during the month of August. 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 Rapid City in August 2025.
If you’re planning to visit Rapid City in the near future, we highly recommend that you review the 14 day weather forecast for Rapid City before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 1° / -7° | 5 | 14 | 13 | 23 mm | Awful | Rapid City in January |
| February | 1° / -8° | 5 | 10 | 14 | 35 mm | Awful | Rapid City in February |
| March | 8° / -2° | 5 | 17 | 10 | 57 mm | Bad | Rapid City in March |
| April | 12° / 1° | 7 | 16 | 7 | 115 mm | Awful | Rapid City in April |
| May | 18° / 7° | 10 | 19 | 2 | 139 mm | Bad | Rapid City in May |
| June | 26° / 13° | 7 | 23 | 0 | 122 mm | Good | Rapid City in June |
| July | 30° / 18° | 7 | 24 | 0 | 117 mm | Ok | Rapid City in July |
| August | 29° / 17° | 6 | 25 | 0 | 96 mm | Good | Rapid City in August |
| September | 24° / 13° | 3 | 27 | 0 | 56 mm | Perfect | Rapid City in September |
| October | 14° / 4° | 3 | 23 | 4 | 63 mm | Ok | Rapid City in October |
| November | 8° / -1° | 3 | 21 | 6 | 25 mm | Bad | Rapid City in November |
| December | 1° / -7° | 3 | 17 | 11 | 30 mm | Awful | Rapid City in December |