Mammoth Lakes Weather in September
What's the weather like in Mammoth Lakes (California) in September 2025?
The climate in Mammoth Lakes during September can be summarized as mild and dry.
September is in the fall / autumn in Mammoth Lakes and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a cool 19°C (67°F), whilst at night 3°C (37°F) is normal.
| Daytime temperature | 19.3°C 66.7°F |
|---|---|
| Nightly temperature | 2.5°C 36.5°F |
| Average temperature | 10.9°C 51.6°F |
| Daily sunshine | 11 hrs |
| Avg rainfall | 20 mm 0.8 ins |
| Rainy days | 5 days |
| Sea temperature | 16.6°C 61.9°F |
| Humidity | 50% |
| Windspeed | 13.3kph 8 mph |
On average September is the driest month of the year in Mammoth Lakes with around 20mm 0.8 inches of rain making it a dry time to visit. This rainfall is typically spread over 5 days, although this may vary considerably.
On the flip side this corresponds to an average of 11 hours of sunshine per day.
September temperatures in Mammoth Lakes
September rainfall
September hourly sunshine
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 Mammoth Lakes in September 2025.
Other monthly averages
Best places to visit in September
Mammoth Lakes weather stats
| Hottest month: | July | 23.6°C 74.5°F |
|---|---|---|
| Driest month: | September | 20mm 0.8ins |
| Sunniest month: | July | 12.8hrs |
| Coldest month: | January | 3.7°C 38.7°F |
| Wettest month: | January | 125mm 4.9ins |
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