Click on a day for an hourly weather forecast
The weather in Sion in August is very cold with temperatures between 4°C and 18°C, warm clothes are a must.
You can expect rain for roughly half of the month of August in Sion. 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 Sion in August 2025.
If you’re planning to visit Sion in the near future, we highly recommend that you review the 14 day weather forecast for Sion before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -1° / -14° | 5 | 6 | 21 | 206 mm | Awful | Sion in January |
| February | 0° / -13° | 5 | 5 | 20 | 149 mm | Awful | Sion in February |
| March | 2° / -10° | 8 | 5 | 20 | 166 mm | Awful | Sion in March |
| April | 6° / -5° | 12 | 7 | 12 | 158 mm | Awful | Sion in April |
| May | 10° / -1° | 20 | 5 | 7 | 298 mm | Awful | Sion in May |
| June | 16° / 2° | 18 | 11 | 1 | 241 mm | Ok | Sion in June |
| July | 18° / 4° | 16 | 15 | 0 | 230 mm | Ok | Sion in July |
| August | 18° / 4° | 14 | 17 | 0 | 207 mm | Ok | Sion in August |
| September | 15° / 2° | 11 | 17 | 2 | 132 mm | Bad | Sion in September |
| October | 10° / -2° | 8 | 18 | 6 | 115 mm | Awful | Sion in October |
| November | 4° / -7° | 7 | 10 | 13 | 157 mm | Awful | Sion in November |
| December | -1° / -12° | 7 | 7 | 18 | 190 mm | Awful | Sion in December |