Cloud cover forecast
You will find below the cloud cover forecast computed by the american model GFS (Global Forecast System) for Europe for the next 5 days. There is a picture every 6 hours (12 a.m., 6 a.m., 12 p.m., 6 p.m.: the time is displayed below each image). The time zone is the UTC zone.
The black areas correspond to the cloudless areas: the sky is perfectly clear and it is possible to observe. For reliable forecasts, compare the forecasts from different models. I use the following in France: