Belmont Weather in September

What's the weather like in Belmont (California) in September 2025?

The climate in Belmont during September can be summarized as warm and very dry.

September is in the fall / autumn in Belmont and is typically the warmest month of the year. Daytime maximum temperatures average around a comfortable 24°C (75°F), whilst at night 13°C (56°F) is normal.

Belmont weather averages (imperial / metric)
Daytime temperature 24.1°C 75.3°F
Nightly temperature 13.2°C 55.7°F
Average temperature 18.6°C 65.5°F
Daily sunshine 10.1 hrs
Avg rainfall 4 mm 0.2 ins
Rainy days 1 days
Sea temperature 14.4°C 57.9°F
Humidity 70%
Windspeed 16.2kph 10 mph

On average September is the 4th driest month of the year in Belmont with around 4mm 0.2 inches of rain making it a very dry time to visit.

On the flip side this corresponds to an average of 10.1 hours of sunshine per day.

September temperatures in Belmont

Belmont average temperature in September

September rainfall

Belmont average rain in September

September hourly sunshine

Belmont 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 Belmont in September 2025.