Last updated: June 24, 2025
In August, the average temperature in Rapid City, United States is a pleasant 20°C (68°F). Expect a range that dips to 5°C (42°F) and peaks at 32°C (90°F). During this month, 91 mm (3.6 in) of precipitation can be expected over approximately 11 days, contributing to an average humidity level of 76%.
In August in Rapid City, the average temperature is 20°C (68°F), with maximums reaching 32°C (90°F) and minimums dropping as low as 5°C (42°F). This varied climate makes it an ideal destination for travelers seeking both warm and cool experiences.
In Rapid City in August, the precipitation amount is 91 mm (3.6 in) over a period of 11 days.
In Rapid City in August, humidity is 76%. With an average temperature of 20°C (68°F), this humidity feels like a warm blanket wrapping around you, making outdoor exploration both exhilarating and slightly stifling, ideal for leisurely strolls but necessitating frequent breaks to hydrate and cool off.
In Rapid City in August, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Rapid City.
UV Risk Categories
Weather in Rapid City varies notably across the year, with each month offering distinct climate conditions. This page compares August’s weather to other months in Rapid City, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -6°C (22°F) | 57 mm (2.2 inches) | 91% | low |
| February Weather | -6°C (22°F) | 62 mm (2.4 inches) | 91% | moderate |
| March Weather | -1°C (31°F) | 62 mm (2.4 inches) | 87% | moderate |
| April Weather | 5°C (42°F) | 97 mm (3.8 inches) | 87% | high |
| May Weather | 13°C (56°F) | 119 mm (4.7 inches) | 82% | very high |
| June Weather | 19°C (66°F) | 111 mm (4.4 inches) | 79% | very high |
| July Weather | 21°C (71°F) | 103 mm (4.1 inches) | 75% | very high |
| August Weather | 20°C (68°F) | 91 mm (3.6 inches) | 76% | very high |
| September Weather | 16°C (61°F) | 78 mm (3.1 inches) | 79% | high |
| October Weather | 10°C (49°F) | 131 mm (5.2 inches) | 83% | moderate |
| November Weather | 2°C (35°F) | 77 mm (3.0 inches) | 86% | moderate |
| December Weather | -2°C (28°F) | 74 mm (2.9 inches) | 87% | low |