Hello,

Be also aware that models can also predict clear sky where there is a high pressure area... But those areas are subject to fog or very low clouds, especially in the morning. Some other local phenomena can be very hard to take into account by computer models (local winds, advection fog)...

The sky can also be clear but "grey" at high altitude because of dense high cloud layers coming from a distant thunderstorm area for exemple...

In the caribbean it can be also very hazy because of fine sand coming from the Sahara. Even without a cloud in the sky, people all agree to say that "weather" is bad or that it's going to rain...

In all those cases, sky is actually clear... but not according to our expectations of a clear sky... or simply not clear from our very precise location (in case of fog, it can be clear less than one kilometer away).

It wasn't sunny but what the weather looked like exactly that particular day?