Mammoth Lakes weather in September
September in Mammoth Lakes: nice, dry, with clean air — not the best time to visit.
#10 of 12 months in Mammoth Lakes · #889 of 897 destinations to visit in September · comfort 24/100 (tier F)
Updated June 2026 · climate normals from ERA5 reanalysis
Traveller notes on Mammoth Lakes in September
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Mammoth Lakes climate normals — September
| Daytime high | 21°C / 70°F | 😎 nice |
|---|---|---|
| Nighttime low | 8°C / 46°F | |
| Rainfall | 11 mm / 0.4 in | ☀️ dry |
| Rainy days | 3 days | |
| Humidity | 54% | 🍃 comfortable |
| Dew point | 2°C / 36°F | |
| Sunshine | 11.5 h/day | |
| Daylight | 12.4 h | |
| Wind | 14 km/h / 9 mph | |
| Snowfall | 0.3 cm / 0.1 in | |
| Air quality (US AQI) | 42 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Mammoth Lakes in September — FAQ
- Is September a good time to visit Mammoth Lakes?
- September in Mammoth Lakes: nice, dry, with clean air — not the best time to visit. It ranks #10 of 12 months for Mammoth Lakes on SeasonMap's comfort score (24/100).
- What is the weather like in Mammoth Lakes in September?
- In September, Mammoth Lakes averages a daily high of 20.9°C and a low of 7.7°C, with about 11.2 mm of rain over roughly 3.4 rainy days.
- What is the air quality in Mammoth Lakes in September?
- Mammoth Lakes has a mean US Air Quality Index of about 42 in September.