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The weather in Snoqualmie Pass in September is very cold with temperatures between 2°C and 20°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Snoqualmie Pass 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.
Our weather forecast can give you a great sense of what weather to expect in Snoqualmie Pass in September 2025.
If you’re planning to visit Snoqualmie Pass in the near future, we highly recommend that you review the 14 day weather forecast for Snoqualmie Pass before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -1° / -10° | 12 | 4 | 18 | 374 mm | Awful | Snoqualmie Pass in January |
| February | 2° / -10° | 12 | 2 | 19 | 331 mm | Awful | Snoqualmie Pass in February |
| March | 4° / -7° | 14 | 3 | 18 | 311 mm | Awful | Snoqualmie Pass in March |
| April | 8° / -4° | 13 | 6 | 12 | 193 mm | Awful | Snoqualmie Pass in April |
| May | 15° / -1° | 12 | 17 | 3 | 150 mm | Bad | Snoqualmie Pass in May |
| June | 19° / 1° | 7 | 23 | 0 | 101 mm | Ok | Snoqualmie Pass in June |
| July | 24° / 3° | 3 | 28 | 0 | 35 mm | Perfect | Snoqualmie Pass in July |
| August | 24° / 4° | 3 | 28 | 0 | 45 mm | Perfect | Snoqualmie Pass in August |
| September | 20° / 2° | 7 | 23 | 0 | 109 mm | Ok | Snoqualmie Pass in September |
| October | 12° / -2° | 11 | 17 | 2 | 281 mm | Awful | Snoqualmie Pass in October |
| November | 4° / -7° | 15 | 5 | 13 | 337 mm | Awful | Snoqualmie Pass in November |
| December | -1° / -11° | 12 | 3 | 21 | 349 mm | Awful | Snoqualmie Pass in December |