Herkimer Weather in September

The climate in Herkimer during September can be summarized as mild and damp.

September is in the fall / autumn in Herkimer and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 21°C (70°F), whilst at night 8°C (47°F) is normal.

On average September is the 3rd wettest month of the year in Herkimer with around 103mm 4 inches of rain making it a damp time to visit. This rainfall is typically spread over 11 days, although this may vary considerably.

On the flip side this corresponds to an average of 7 hours of sunshine per day.

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 Herkimer in September 2025.