Los Alamos Weather in September

The climate in Los Alamos during September can be summarized as mild and very dry.

September is in the fall / autumn in Los Alamos and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around 24°C (75°F), whilst at night 11°C (52°F) is normal.

On average September is the 5th driest month of the year in Los Alamos with around 8mm 0.3 inches of rain making it a very dry time to visit.

On the flip side this corresponds to an average of 9.7 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 Los Alamos in September 2025.