Reading Lake Geneva weather: forecast, stations and radar

Forecast or measurement?

Two different things, not to be confused:

• Measurement: the wind blowing right now, recorded every 10 minutes by MeteoSwiss's SwissMetNet stations on the lakeshore, gusts included. It's the truth of the moment, but only where the station is.
• Measurement on the water: the LéXPLORE research station, on the lake off Pully, and three club wind beacons of the OpenWindMap network. They see the wind at lake level; the beacons are not official stations.
• Forecast: wind and rain calculated hour by hour by MeteoSwiss's ICON-CH1 model, over the whole lake. It gives the trend; the exact time and place of a gust or shower can change.
• Radar: the rain falling right now, one image every 5 minutes. The app extends its movement over the coming hour (extrapolation, reliable for about half an hour); it cannot see a shower forming on the spot.

What the water is doing

• Currents and water temperature: calculated by Eawag's 3D model (Alplakes), in three-hour slots. On Lake Geneva the current rarely exceeds 0,3 kn, but on a long leg it pushes you sideways.
• Waves: on Lake Geneva no wave measurements are published in time; the app estimates them from the wind and the stretch of open water in front of the point (the fetch). An estimate, never a measurement.
• Lake level: measured by the Federal Office for the Environment, it matters for the actual depth near the shore.

A routine before setting off

1. The day before: the next day's forecast, hour by hour, to pick your window.
2. In the morning: the nearest stations — does the real wind match the forecast?
3. Before casting off: the radar, and the sky towards the Jura and towards Savoy.
4. On the water: the storm warning lights, and the app's thunderstorm alert.

With the Navleman map

Menu Wind and weather: stations, forecast wind (arrows or animation), rain, thunderstorm risk, radar, named winds, currents, water temperature and fog; the time slider scrolls through the hours. Menu Lake info: lake level and estimated waves.

Open the Lake Geneva map

See also

The Winds and weather guide, plus: Lake Geneva's winds, Thunderstorms and storm warnings.