When I set this option in SGP, the reading for “Cloud Cover” seems to be completely wrong. Specifically, when the sky was completely overcast, the Cloud Cover was stated to be “0%”. Now the reading is 12%, and there is not much sign of any clear sky.
Is it possible that the reading is “back to front”, i.e. that 0% cloud cover means overcast, and 100% cloud cover means clear?
If so, is the mistake in SGP or in the OpenWeatherMap data?
I also note that the values for seeing and sky brightness are both “NA”, which would make sense for a cloudy condition.