Castle Rock Weather in September

What's the weather like in Castle Rock (Colorado) in September 2025?

The climate in Castle Rock during September can be summarized as mild and reasonably dry.

September is in the fall / autumn in Castle Rock and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 24°C (75°F), whilst at night 6°C (43°F) is normal.

Castle Rock weather averages (imperial / metric)
Daytime temperature 23.9°C 74.9°F
Nightly temperature 6°C 42.7°F
Average temperature 14.9°C 58.8°F
Daily sunshine 9.8 hrs
Avg rainfall 31 mm 1.2 ins
Rainy days 7 days
Sea temperature 18.3°C 65°F
Humidity 50%
Windspeed 15.5kph 10 mph

On average September is the 6th driest month of the year in Castle Rock with around 31mm 1.2 inches of rain making it a reasonably 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 9.8 hours of sunshine per day.

September temperatures in Castle Rock

Castle Rock average temperature in September

September rainfall

Castle Rock average rain in September

September hourly sunshine

Castle Rock 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 Castle Rock 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

Castle Rock weather stats

Castle Rock weather statistics
Hottest month: July 29.3°C 84.7°F
Driest month: January 12mm 0.5ins
Sunniest month: September 9.8hrs
Coldest month: January 6°C 42.8°F
Wettest month: May 64mm 2.5ins
Map showing location of Castle Rock (39.37221, -104.85609) Castle Rock map pin © Google

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