Click on a day for an hourly weather forecast
The weather in Mammoth in September is very cold with temperatures between 3°C and 16°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Mammoth during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
You can expect a few days of snow in Mammoth during September. It’s important to get out your snow boots and warm mittens to stay warm while you explore Mammoth.
Our weather forecast can give you a great sense of what weather to expect in Mammoth in September 2025.
If you’re planning to visit Mammoth in the near future, we highly recommend that you review the 14 day weather forecast for Mammoth before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -6° / -15° | 3 | 5 | 24 | 112 mm | Awful | Mammoth in January |
| February | -6° / -15° | 4 | 1 | 25 | 118 mm | Awful | Mammoth in February |
| March | -1° / -11° | 6 | 1 | 27 | 129 mm | Awful | Mammoth in March |
| April | 2° / -8° | 7 | 2 | 26 | 141 mm | Awful | Mammoth in April |
| May | 9° / -3° | 15 | 2 | 22 | 163 mm | Awful | Mammoth in May |
| June | 16° / 3° | 10 | 11 | 8 | 113 mm | Bad | Mammoth in June |
| July | 22° / 7° | 6 | 25 | 1 | 56 mm | Good | Mammoth in July |
| August | 21° / 6° | 7 | 23 | 1 | 67 mm | Ok | Mammoth in August |
| September | 16° / 3° | 6 | 19 | 5 | 76 mm | Ok | Mammoth in September |
| October | 6° / -4° | 7 | 7 | 17 | 94 mm | Awful | Mammoth in October |
| November | -2° / -10° | 4 | 6 | 21 | 100 mm | Awful | Mammoth in November |
| December | -7° / -16° | 3 | 3 | 25 | 111 mm | Awful | Mammoth in December |