Grand Junction Weather in September

What's the weather like in Grand Junction (Colorado) in September 2025?

The climate in Grand Junction during September can be summarized as warm and dry.

September is in the fall / autumn in Grand Junction and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a comfortable 27°C (81°F), whilst at night 10°C (50°F) is normal.

Grand Junction weather averages (imperial / metric)
Daytime temperature 27.4°C 81.3°F
Nightly temperature 10°C 50°F
Average temperature 18.7°C 65.7°F
Daily sunshine 10.4 hrs
Avg rainfall 21 mm 0.8 ins
Rainy days 6 days
Sea temperature 17.6°C 63.7°F
Humidity 40%
Windspeed 14.8kph 9 mph

On average September is the 5th wettest month of the year in Grand Junction with around 21mm 0.8 inches of rain making it a dry time to visit. This rainfall is typically spread over 6 days, although this may vary considerably.

On the flip side this corresponds to an average of 10.4 hours of sunshine per day.

September temperatures in Grand Junction

Grand Junction average temperature in September

September rainfall

Grand Junction average rain in September

September hourly sunshine

Grand Junction 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 Grand Junction 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

Grand Junction weather stats

Grand Junction weather statistics
Hottest month: July 33.6°C 92.5°F
Driest month: June 12mm 0.5ins
Sunniest month: June 12.6hrs
Coldest month: January 1.9°C 35.4°F
Wettest month: October 25mm 1ins
Map showing location of Grand Junction (39.06387, -108.55065) Grand Junction map pin © Google

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