Weather in Switzerland in September

How September compares

September is the 4th warmest month of the year in Switzerland. Against London's average high of 18.6°C in September, Switzerland is 0.2°C warmer by day and 0.2°C cooler at night.

Daytime and night-time in September

The typical September day in Switzerland peaks at 18.8°C, but that is an average: the warmest 10% of days reach 24.2°C or more. Roughly 1 in 17 days top 25°C. Nights average 11.0°C; one night in ten drops to 7.2°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest September day here reached 28.8°C (2009-09-01) and the coldest night 2.7°C (2002-09-25).

Rain in September

Wet (more than 8 rainy days): about 12 days with 1 mm or more, 122 mm in total. Year to year it varies a lot - the wettest September was 1998 with 209 mm, the driest 2020 with 55 mm. Humidity averages 79%.

Sunshine and daylight

Around 4.6 hours of sunshine a day (estimated from cloud cover), 12.3 hours of daylight: the sun rises about 07:03 and sets about 19:39 local time in mid-September. Average cloud cover is 63%.

Is September a good time to visit Switzerland?

September is not the strongest month here: mild days and frequent rain. The best months for Switzerland on our scoring are July, August, June.

Comfortable days, with layers needed after dark

The main advantage of September is that daytime temperatures generally suit being active without much heat to manage. A light layer over a T-shirt gives you flexibility, while a jumper or jacket will be useful when you stop or head out in the evening. Warmer days can reach around 24°C or more, so there is still a place for lighter clothing in your bag. The catch is the cooler end of the range: colder nights can fall to around 7°C or below. Pack for that variation rather than treating the average as a promise, particularly if you like spending evenings outside.

Plan around rain rather than expecting clear skies

Rain is the bigger compromise. With about 12 rainy days in September, a waterproof jacket and shoes that cope with wet conditions are more useful than packing solely for fair weather. That does not mean every affected day is a washout, but it does make a flexible itinerary sensible. Sunshine averages about 4.6 hours within 12.3 hours of daylight, so daylight should not be confused with clear skies. Keep outdoor plans movable and have an indoor alternative ready when the forecast looks poor. September suits travellers who can accept weather changes; it is less convincing if dry days are central to the trip.