Sion weather in September
Temperature, rain and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Good
Best time to visit: May – October
What is the weather like in Sion in September?
In September, Sion is mild: daytime highs average 21 °C, and nights cool down to about 11 °C. The sun shines for around 7 hours a day. Rain is frequent, with about 13 rainy days and 126 mm in total. All in all, September is a good month for a holiday in Sion.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 72 | 73 | 68 |
| Day | 25° | 21° | 17° |
| Night | 14° | 11° | 6° |
| Sun | 8 h | 7 h | 5 h |
| Rain days | 16 | 13 | 13 |
More details for September
- Daylight
- 12 h 38 min07:07 – 19:45
- UV index
- 5 · moderateclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 8 km/haverage daily peakAll months
- Cloud cover
- 62 %on averageAll months
- Hot days
- 0 days30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC+2Europe/Zurich
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %65 %
- Few rainy daysweight 30 %34 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Mountain air”.
What to pack in September
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Sion in September: quick answers
Is Sion hot in September?
No. In September, Sion is mild: daytime highs average 21 °C and nights drop to about 11 °C.
Does it rain much in Sion in September?
Rain is frequent, with about 13 rainy days and 126 mm in total.
Sion month by month
The whole year in SionAll destinations: SwitzerlandWhere to go in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences