In September sea water temperature in some cities on the Lake Geneva coast is above 20°C and it is enough for comfortable bathing. The warmest average water temperature Lake Geneva in September is 20.1°C (in Bourg-en-Lavaux, Switzerland), and the coldest sea surface temperature is 19.2°C (in Coppet, Switzerland). To find out the water temperature today and in the coming days, go to Current water temperature of the Lake Geneva
This data on the average monthly surface water temperature on the Lake Geneva coast in September. To see the details, select the country and then the city of your interest. Besides water temperature, you can also get information about the weather for today, tomorrow and the upcoming days, surf forecast, as well as the data on sunrise/sunset and moonrise/moonset at a given point on any given day.