Weather in Basel in September 2025
Average weather
Average temperature in Basel in September
Going from a maximum of +32°C during the day to a minimum of +8°C during the night, the temperature in September averages around +26°C.
The average maximum temperature goes down 17% by the end of the month, compared with the beginning of the month, from +26°C to +22°C.
Is Basel warm or cold in September?
Basel is typically mild in September.
Maximum temperatures go down compared to the previous month from +25°C to +21°C. The minimum temperature also goes down from +15°C to +11°C.
Pack a light jacket as it will be warm in the day and cool in the evenings.
Take a look at how September is compared to other months in Basel:
Climate in Basel in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +25°C | +21°C | +16°C | ||||
| Min. temperature | ||||||
| +6°C | +2°C | -4°C | ||||
| Max. temperature | ||||||
| +39°C | +32°C | +30°C | ||||
| Rainfall | ||||||
| 120 mm | 86 mm | 87 mm | ||||
| Wind | ||||||
| 1 m/s | 1 m/s | 1 m/s | ||||
| Humidity | ||||||
| 72% | 77% | 82% | ||||
| Air pressure | ||||||
| 1016 HPa | 1017 HPa | 1017 HPa | ||||
| Sunny days | ||||||
| 7 | 6 | 4 | ||||
| Cloudy days | ||||||
| 4 | 6 | 10 | ||||
| Rainy days | ||||||
| 15 | 16 | 17 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September typically has worse weather conditions compared to August. It’s getting colder in September. From +25°C in the day, the average maximum temperature lowers to +21°C. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 120 mm to 86 mm. Humidity rises from 72% to 77%. The average wind speed doesn’t change much during September, staying around 1 m/s. The days becoming less sunny, going from 7 sunny days in August to 6 in September.
October brings much the same weather, it remains ok.
Wind
The average wind speed is 2 m/s getting up to 3 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Basel is gradually decreasing during September, going from 2 m/s to 1 m/s over the course of the month.
Rain
How was the weather last September in Basel?
Climate Change over Years
The climate in Basel in September has not changed much over the last 43 years.
The average temperature was the lowest in 1980 (+14°C) and the highest in 2022 (+18°C). The driest year was 1991 with only 753 mm of rainfall, and the wettest year was 2016 with 1490 mm.
FAQ
Is September a good time to visit Basel?
Can you sunbathe in Basel in September?
Is Basel rainy in September?
Is it sunny in Basel in September?
Other cities in Switzerland
Monthly weather in Basel
Source of the data
For this page, we’ve looked at the typical weather in Basel, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.