Helena Weather in September

What's the weather like in Helena (Montana) in September 2025?

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

September is in the fall / autumn in Helena and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a cool 20°C (69°F), whilst at night 4°C (39°F) is normal.

Helena weather averages (imperial / metric)
Daytime temperature 20.4°C 68.6°F
Nightly temperature 4.1°C 39.3°F
Average temperature 12.2°C 54°F
Daily sunshine 9.1 hrs
Avg rainfall 30 mm 1.2 ins
Rainy days 8 days
Sea temperature 13.7°C 56.7°F
Humidity 55%
Windspeed 13.7kph 9 mph

On average September is the 5th wettest month of the year in Helena with around 30mm 1.2 inches of rain making it a dry time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.1 hours of sunshine per day.

September temperatures in Helena

Helena average temperature in September

September rainfall

Helena average rain in September

September hourly sunshine

Helena 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 Helena 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

Helena weather stats

Helena weather statistics
Hottest month: July 27.9°C 82.2°F
Driest month: February 12mm 0.5ins
Sunniest month: July 12.8hrs
Coldest month: January -1.3°C 29.7°F
Wettest month: June 55mm 2.2ins
Map showing location of Helena (46.59271, -112.03611) Helena map pin © Google

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