Lac Léman water temperature
Lac Léman, Thonon-les-Bains · Lake
The current water temperature at Lac Léman is 19.7 °C (as of September 20, 2026, source: Eawag/Alplakes model).
Lakes stratify in summer: bathing-warm on top, markedly colder a few metres down. Measurements are taken at the surface — right where you swim.
Measurement series & statistics
This measurement series includes 473 data points since July 22, 2026.
Lowest recorded value: 19.1 °C on September 10, 2026 · highest value: 27.5 °C on August 13, 2026.
In September, temperatures have ranged between 19.1 °C and 24.1 °C.
The current value is 2.3 °C below the September average of this series.
Nearby waters
More measuring points: Lac Léman
Frequently asked questions
Can you swim at Lac Léman right now?
The current water temperature is 19.7 °C. See live swimming conditions, weather and quality in the BrrChecker app.
How warm is the water at Lac Léman?
Currently 19.7 °C (updated continuously).
How warm is at Lac Léman in September?
In September, the water temperature recently averaged 22.0 °C.
When is the water warmest at Lac Léman?
Across the measurement record, July is on average the warmest month (25.1 °C).
