Fort Collins Weather in September

What's the weather like in Fort Collins (Colorado) in September 2025?

The climate in Fort Collins during September can be summarized as mild and reasonably dry.

September is in the fall / autumn in Fort Collins and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 24°C (75°F), whilst at night 8°C (46°F) is normal.

Fort Collins weather averages (imperial / metric)
Daytime temperature 23.6°C 74.5°F
Nightly temperature 7.6°C 45.7°F
Average temperature 15.6°C 60.1°F
Daily sunshine 9.6 hrs
Avg rainfall 32 mm 1.3 ins
Rainy days 7 days
Sea temperature 17.6°C 63.7°F
Humidity 50%
Windspeed 15.8kph 10 mph

On average September is the 6th driest month of the year in Fort Collins with around 32mm 1.3 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 9.6 hours of sunshine per day.

September temperatures in Fort Collins

Fort Collins average temperature in September

September rainfall

Fort Collins average rain in September

September hourly sunshine

Fort Collins 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 Fort Collins 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

Fort Collins weather stats

Fort Collins weather statistics
Hottest month: July 29.3°C 84.7°F
Driest month: February 11mm 0.4ins
Sunniest month: September 9.6hrs
Coldest month: January 4.6°C 40.3°F
Wettest month: May 70mm 2.8ins
Map showing location of Fort Collins (40.58526, -105.08442) Fort Collins map pin © Google

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