Last updated: March 2, 2024
The weather in Rapid City, United States, during September is characterized by an average temperature of 16°C (62°F). Highs can soar to 33°C (92°F), while lows may dip to 2°C (35°F). Typically, the humidity level in Rapid City throughout September hovers around 76%.
Minimum temperature
Average temperature
Maximum temperature
Humidity
In September, Rapid City averages 43 mm (1.7 inches) of rainfall, typically over the course of 7 rainy days. The month enjoys an average of 12 hours 26 minutes of daylight, with the sun shining for approximately 9 hours 35 minutes each day. Additionally, there is a 67% probability of sunny days during this period.
Precipitation
Rainy days
Sunshine hours
Chance of sun
In September, the UV Index in Rapid City reaches a maximum of 8, indicating a level of VeryHigh exposure. The most intense UV radiation typically occurs between 12:00 and 14:00, during which unprotected skin may burn in as little as 15 minutes.
| 07:00 | 08:00 | 09:00 | 10:00 | 11:00 | 12:00 | 13:00 | 14:00 | 15:00 | 16:00 | 17:00 | 18:00 | 19:00 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UVI | 1 | 1 | 3 | 5 | 6 | 8 | 8 | 7 | 5 | 4 | 2 | 1 | 1 |
| Exposure | Low | Moderate | High | VeryHigh | High | Moderate | Low | ||||||
| Time to burn | 45 min | 30 min | 25 min | 15 min | 25 min | 30 min | 45 min | ||||||