Mammoth Lakes, CA weather in September
In September, Mammoth Lakes sees highs around 71°F and lows around 40°F: mild and dry. There are about 2 days with rain. Great for outdoor plans.
- Normal high
- 71°F
- Normal low
- 40°F
- Wet days
- 2
- 0.5 in total
- Daylight
- 12.4 h
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 75°F | 66°F |
| Normal low | 45°F | 35°F |
| Sunrise / sunset | 6:26 am / 7:25 pm | 6:50 am / 6:41 pm |
| Daylight | 13.0 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Pacific Time).
What kind of days to expect
- Comfortable dayshigh 65-80°F (temperature only: no humidity station nearby)24 of 30
- Hot dayshigh 90°F or more0 of 30
- Wet daysat least 0.01 in of rain or melted snow2 of 30
- Notable rainat least 0.10 in1 of 30
- Freezing nightslow 32°F or below5 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 0.5 in. Days with half an inch or more are rare. Snow is very rare.
How September varies from year to year
- Warmest September, 1991-20202009: average high 74°F
- Coolest September2005: average high 66°F
- Wettest September1999: 1.8 in
- Driest September1996: no measurable precipitation
- Highest reading83°F (September 2, 2014)
- Lowest reading21°F (September 21, 2004)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 77°F | 71°F | 61°F |
| Normal low | 47°F | 40°F | 30°F |
| Wet days | 2 | 2 | 4 |
| Comfortable days | 23 | 24 | 12 |
| Daylight | 13.6 h | 12.4 h | 11.2 h |
Highs change by -6°F from August and -10°F into October.
Nearby alternatives in September
- Warmer: Yosemite Valley, CA34 mi · high 83°F · 2 wet days
How Mammoth Lakes ranks in September
- Normal high334th warmest of 378 cities; 57th of 60 in California
- Wet days63rd driest of 378
What to pack for Mammoth Lakes in September
- A warm jacket – lows near 40°F, highs near 71°F
- Layers – afternoons near 71°F but nights near 40°F
Frost in September
The first fall frost typically comes around Sep 17; in 1 year in 10 it comes before Sep 2. All frost dates for Mammoth Lakes.
Heating and cooling
September has 286 heating degree days and 2 cooling degree days (base 65°F), 4% of the year's total heating and cooling demand.
Questions
How hot is Mammoth Lakes in September?
The normal high is 71°F and the normal low is 40°F. From 1991 to 2020 the hottest September reading was 83°F (September 2, 2014).
Does it rain a lot in Mammoth Lakes in September?
About 2 days in September have at least 0.01 in of precipitation, and the normal total is 0.5 in. The wettest September in 1991-2020 was in 1999 (1.8 in); the driest was in 1996, with no measurable precipitation.
Does it snow in Mammoth Lakes in September?
Snow is very rare: the 1991-2020 normal for September rounds to 0.0 in.
Is September a good time to visit Mammoth Lakes?
September ranks 3rd of 12 months on our comfort score for Mammoth Lakes (85 out of 100). It has about 24 comfortable days (judged by temperature only). The best months are June, August and September.
Where the numbers come from
- Temperature, rain and frost dates: Mammoth Lakes RS (USC00045280), 0.6 mi E of the city center, 7,804 ft (69 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Snowfall and snow depth: Lee Vining (USC00044881), 23 mi NNW of the city center, 6,797 ft (1,076 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Not available for this location: humidity and wind by hour, cloud cover and daily humidity and wind (no station close enough or similar enough in elevation).