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Basel in September: Weather, Average temperature and Climate

Planning a trip and want to know what the weather in Basel in September will be like? Take a look at our weather guide for Basel, based on historical data.
Check flight prices to Basel on Avionero:
September

Weather in Basel in September 2025

OK Weather
Mild
🌧️
Rainy
If you plan to visit Basel in September, the weather is typically alright, with an average high temperature of +21°C during the day and approximately 6 sunny days. Expect some rainy, though, as there are typically 16 rainy days in the month and around 86 mm of precipitation. The weather is changeable so you may have to pack for every eventuality. Search flights in one click on Avionero.

Average weather

☀️
+21°C
Avg. max. temperature
+2°C
Min.
+32°C
Max.
86 mm
Total precipitation
77%
Avg. humidity
1 m/s
Avg. wind
6 ☀️
Sunny Days
6 ⛅️
Cloudy
16 🌦
Rainy
Our opinion: Basel has OK weather in September.

Average temperature in Basel in September

Here are the expected maximum, average and minimum temperatures in Basel for September based on the historical data.
Last Year
Historical Data

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

Basel weather looks like this, on average, in September and the surrounding months.
AugustSeptemberOctober
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 mm86 mm87 mm
Wind
1 m/s1 m/s1 m/s
Humidity
72%77%82%
Air pressure
1016 HPa1017 HPa1017 HPa
Sunny days
764
Cloudy days
4610
Rainy days
151617
Snowy days
000

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

Wind speed in Basel in September based on historical data.
Last Year
Historical Data

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

Amount of rainfall in mm during September in Basel based on historical data.
Last Year
Historical Data
Typically, there is a 33% chance of rain on an average day in September, with total rainfall of approximately 55 mm. The maximum amount of rainfall per day is around 20 mm, which is considered light rain. September is a pretty wet month with over 10 rainy days, so don’t forget to pack an umbrella, raincoat, and a pair of galoshes.
Here’s how September is compared with other months in the amount of precipitation, total mm:
Basel wettest month is May, where a typical day has a 58% chance of precipitation and 129 mm of rainfall per day. February, on the other hand, is the driest month with a mere 34% chance of precipitation and 58 mm of rainfall per day.

How was the weather last September in Basel?

This is the weather in Basel in September 2023:
1 September
☀️
+26°C
2 September
☀️
+29°C
3 September
☀️
+28°C
4 September
☀️
+28°C
5 September
☀️
+29°C
6 September
☀️
+28°C
7 September
☀️
+30°C
8 September
☀️
+31°C
9 September
☀️
+31°C
10 September
☀️
+31°C
11 September
☀️
+32°C
12 September
☀️
+31°C
13 September
🌧️
+23°C
14 September
☁️
+23°C
15 September
☀️
+25°C
16 September
☀️
+27°C
17 September
☀️
+30°C
18 September
🌧️
+22°C
19 September
🌧️
+24°C
20 September
☀️
+26°C
21 September
☀️
+26°C
22 September
🌧️
+19°C
23 September
☀️
+19°C
24 September
☀️
+20°C
25 September
☀️
+22°C
26 September
☀️
+24°C
27 September
☀️
+25°C
28 September
☀️
+27°C
29 September
☀️
+27°C
30 September
☀️
+22°C
In September 2023 Basel had 25 sunny days, 1 cloudy days, and 4 rainy days. The average maximum temperature was +26°C, with an absolute maximum of +32°C and a minimum of +19°C. The average humidity was 76%, with a maximum of 100% and a minimum of 31%. The average wind speed was 2 m/s, with a maximum of 8 m/s and a minimum of 0 m/s.
Are you planning a trip in September?

Climate Change over Years

This is how Basel climate have been changing during last 43 years period.

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

Frequently asked questions about the weather in Basel in September:

Is September a good time to visit Basel?

It’s always a good time to visit Basel, but the weather is changeable in September, so plan a mix of indoor and outdoor activities and exploring, and pack for every eventuality.

Can you sunbathe in Basel in September?

September has mild temperatures in Basel. Not ideal for sunbathing, but still good for daytime outdoor activities, but plan for cool evenings. Pack a light jacket and shorts!

Is Basel rainy in September?

Basel is often rainy in September. You may get a bit damp when outside, so pack an umbrella, and maybe even a raincoat.

Is it sunny in Basel in September?

Usually, it’s not very sunny in Basel in September, often it’s pretty cloudy. Pack for any eventuality; layering can help reduce the number of bulky items needed.

Other cities in Switzerland

Check out the weather for 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.