Cloud cover, no need to explain I think.

The seeing corresponds to the size of a star seen on a photo or in an eyepiece. The lower this value is, the more details can be seen especially on the planets and the Moon.The seeing is expressed in seconds of arc ("). The model takes into account the movements of fluid particles in the atmosphere as well as their density. The seeing calculation is experimental. Remarks are welcome to try to improve the model and consequently the forecast.

The higher the value, the less bright the stars. It is expressed in magnitude per air mass. The model takes into account the humidity, temperature and the amount of ozone. The higher the humidity, the more the stars are extinguished, so the extinction value is high.

It’s the horizontal wind speed calculated for a height of 10 meters above the ground. This speed is expressed in km/h.

Is the relative humidity of the air calculated for a height of 2 meters above the ground. It is expressed in %.

Weather data provided by OpenWeather , for more information click here. the cloud cover, wind and humidity data is updated around 01:00, 07:00, 13:00, and 19:00 UTC. The seeing and transparency data are updated every 3 hours. An optimal forecast for an evening of observation is indicated by the green color. "Tonight's Forecast" are calculated in relation to the forecasts of 0h, 1h and 2h.