In short
My Lake shows the water temperature 70 cm below the surface, in front of each of the 65 beaches, updated every three hours from Eawag’s Alplakes model. It can differ by several degrees from one beach to another on the same day, and drop sharply when a strong wind brings cold water up from the depths: this is called “upwelling”.
How is Lake Geneva’s temperature calculated?
The figures come from Alplakes, the platform run by Eawag, the Swiss Federal Institute of Aquatic Science and Technology. It combines numerical lake models and satellite data to calculate water temperature at different depths, with forecasts several days ahead. Eawag reports an error of about 1 °C at the surface for large lakes.
My Lake reads the model value in front of each beach, at 70 cm depth, every three hours. The data are published under a CC BY 4.0 licence.
Why 70 cm below the surface?
Because that is roughly the water you swim in. The very top layer warms or cools very quickly with sun and air; a little deeper, the value is more stable and closer to what you feel when you get in.
Why isn’t the water the same temperature everywhere?
Lake Geneva is large and deep, and wind moves its surface water around. When a strong wind blows for a long time in the same direction, it pushes the warm surface water away; to compensate, cold deep water rises near some shores. Scientists call this upwelling.
- In June 2025, the water near Geneva dropped from 19 to 11 °C within a few days under a strong, persistent south-westerly; Alplakes had forecast it several days ahead (Eawag).
- The known record: at the end of June 2017, the water at the Bains des Pâquis fell from 23 to barely 8 °C in two days (Eawag).
As a result, two beaches can be several degrees apart on the same day. The current spread is calculated below.
Where can you check Lake Geneva’s temperature live?
In the My Lake app, free and with no account, with wind, bise and a verdict for each activity. The list of all 65 beaches also has one page per beach, from Geneva to Saint-Gingolph and from Évian to Chens-sur-Léman.
Lake Geneva’s water right now
Each beach’s water temperature is in the My Lake app, updated every three hours.