Niigata Weather in September

The climate in Niigata during September can be summarized as warm, humid and wet.

September is in the fall / autumn in Niigata and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a muggy 26°C (79°F), whilst at night 18°C (65°F) is normal.

On average September is the 5th wettest month of the year in Niigata with around 158mm 6.2 inches of rain making it a wet time to visit. This rainfall is typically spread over 19 days, although this may vary considerably.

On the flip side this corresponds to an average of 5 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 Niigata in September 2025.