Basel Weather in September
Basel in September sees pleasant temperatures, with highs around 21°C (70°F) and overnight lows of 10°C (50°F). Rainfall is fairly high at around 97 mm (3.8 in) on average, so pack waterproofs just in case.
Rainfall in Basel in September
You can typically expect 12 days of rain this month, averaging around 97 mm (3.8 in). Individual showers can be quite heavy this month. A proper umbrella or rain jacket is worth having.
Temperature in Basel in September
September is a excellent month in Basel, with 21°C (70°F) during the day and 10°C (50°F) at night. Conditions are often most pleasant around the middle of the day. At 10°C (50°F) overnight, it can feel quite a bit cooler after dark. Worth packing something warmer for evenings, but the cooler temperatures are ideal for sleeping.
Sunshine in Basel in September
You can expect a moderate amount of sunlight, with approximately 162 hours. This means a pleasant mix of sun and overcast.If you're a fan of comfortable temperatures and drier conditions, September is a great time to visit.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Switzerland, check out our Basel's climate page.
Basel Temperature in September
Min Temperature
10°C (50°F)
Max Temperature
21°C (70°F)
Chance of Rain
41%
Precipitation
97 mm (3.8 in)
Rainy days
12 days
Humidity
77%
Sunshine
162 hours
Percentage Sunshine
47%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Basel typically drop from around 22°C (72°F) at the start of September to approximately 19°C (66°F) by the end. Nights are cool, with lows typically ranging from 9°C (48°F) to 13°C (55°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Basel in September
Browse day-by-day weather records for Basel spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Basel historical weather extremes in September
Based on 49 years of weather observations in Basel between 1976 and 2025, these are the recorded extremes.
- On September 11, 2023, temperatures climbed to 32°C (90°F), marking the warmest September day on record.
- On September 24, 2002, Basel saw its coldest September day with temperatures maxing out at 8°C (46°F).
- Basel registered its coldest September night on September 30, 1995, with temperatures dropping to 1°C (34°F).
- The heaviest September precipitation occurred on September 1, 1981, when 54 mm (2.1 in) of precipitation fell.
Best Places in Switzerland in September
Find out more about the weather in Switzerland and which places have the best travel conditions in this month. See all of Switzerland in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Basel in September
For Basel in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. High rain levels are expected, so pack waterproof gear and an umbrella or poncho. It won't hurt to bring your sunglasses along, as you'll see some sunny periods.What To Do in Basel in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Switzerland, check out our Basel's climate page.
Temperature Rainfall Sunshine Humidity
See the full Basel climate overview or explore weather in Switzerland.
