Rapid City Weather in September

What's the weather like in Rapid City (South Dakota) in September 2025?

The climate in Rapid City during September can be summarized as mild and dry.

September is in the fall / autumn in Rapid City and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 23°C (74°F), whilst at night 7°C (45°F) is normal.

Rapid City weather averages (imperial / metric)
Daytime temperature 23.1°C 73.6°F
Nightly temperature 7.1°C 44.8°F
Average temperature 15.1°C 59.2°F
Daily sunshine 9.4 hrs
Avg rainfall 30 mm 1.2 ins
Rainy days 7 days
Sea temperature 15.7°C 60.3°F
Humidity 54%
Windspeed 18kph 11 mph

On average September is the 6th wettest month of the year in Rapid City with around 30mm 1.2 inches of rain making it a dry time to visit. This rainfall is typically spread over 7 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.4 hours of sunshine per day.

September temperatures in Rapid City

Rapid City average temperature in September

September rainfall

Rapid City average rain in September

September hourly sunshine

Rapid City average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Rapid City in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Rapid City weather stats

Rapid City weather statistics
Hottest month: July 29.5°C 85.1°F
Driest month: January 8mm 0.3ins
Sunniest month: August 11.2hrs
Coldest month: January 1.2°C 34.2°F
Wettest month: May 80mm 3.1ins
Map showing location of Rapid City (44.08054, -103.23101) Rapid City map pin © Google

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