· Ines Marchetti
Eleven cloudy nights
We publish the cloud figure because the number is good. Here is how it is counted, so you can check it against anywhere else.
A night counts as cloudy if more than half the sky is obscured for more than half the hours of astronomical darkness. By that definition the Ossara averages eleven a year, clustered almost entirely in January and February.
Most sites quote 'clear days', which is a meteorological measure taken at noon and has close to no bearing on whether you can observe. Some quote 'sunshine hours', which is worse. Neither tells you anything about the sky you are paying to look at.
If you are comparing us against somewhere else, ask them for nights, not days, and ask where the number came from.