Basel weather in September
September in Basel: nice, a little rain, with clean air — an excellent time to visit.
#3 of 12 months in Basel · #126 of 604 destinations to visit in September · comfort 87/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Basel climate normals — September
| Daytime high | 22°C / 72°F | 😎 nice |
|---|---|---|
| Nighttime low | 12°C / 54°F | |
| Feels like (high) | 22°C / 72°F | |
| Rainfall | 79 mm / 3.1 in | 🌦 some rain |
| Rainy days | 10 days | |
| Humidity | 74% | 💧 humid |
| Dew point | 12°C / 54°F | |
| Sunshine | 9.4 h/day | |
| Daylight | 12.6 h | |
| Wind | 11 km/h / 7 mph | |
| Air quality (US AQI) | 45 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Basel in September — FAQ
- Is September a good time to visit Basel?
- September in Basel: nice, a little rain, with clean air — an excellent time to visit. It ranks #3 of 12 months for Basel on SeasonMap's comfort score (87/100).
- What is the weather like in Basel in September?
- In September, Basel averages a daily high of 22.2°C and a low of 12.2°C, with about 78.6 mm of rain over roughly 10.2 rainy days.
- What is the air quality in Basel in September?
- Basel has a mean US Air Quality Index of about 45 in September.