Click on a day for an hourly weather forecast
The weather in Sarnen in September is very cold with temperatures between 4°C and 13°C, warm clothes are a must.
You can expect rain for roughly half of the month of September in Sarnen. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Our weather forecast can give you a great sense of what weather to expect in Sarnen in September 2025.
If you’re planning to visit Sarnen in the near future, we highly recommend that you review the 14 day weather forecast for Sarnen before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -2° / -10° | 9 | 7 | 15 | 149 mm | Awful | Sarnen in January |
| February | -1° / -9° | 9 | 5 | 15 | 115 mm | Awful | Sarnen in February |
| March | 2° / -6° | 11 | 10 | 11 | 144 mm | Awful | Sarnen in March |
| April | 6° / -3° | 12 | 14 | 4 | 172 mm | Awful | Sarnen in April |
| May | 9° / 1° | 19 | 11 | 1 | 294 mm | Bad | Sarnen in May |
| June | 14° / 5° | 18 | 12 | 0 | 294 mm | Ok | Sarnen in June |
| July | 17° / 7° | 17 | 14 | 0 | 287 mm | Ok | Sarnen in July |
| August | 17° / 8° | 16 | 15 | 0 | 274 mm | Ok | Sarnen in August |
| September | 13° / 4° | 10 | 20 | 0 | 152 mm | Bad | Sarnen in September |
| October | 8° / 0° | 8 | 22 | 1 | 146 mm | Bad | Sarnen in October |
| November | 3° / -4° | 8 | 15 | 7 | 139 mm | Awful | Sarnen in November |
| December | -1° / -8° | 8 | 11 | 12 | 129 mm | Awful | Sarnen in December |