Overcast

Overcast or overcast weather, as defined by the World Meteorological Organization, is the meteorological condition of clouds obscuring at least 95% of the sky.

[1] However, the total cloud cover must not be entirely due to obscuring phenomena near the surface, such as fog.

[1][3] An overcast sky may be explicitly identified as thin (mostly transparent), but otherwise considered opaque—which always constitutes a ceiling in aviation meteorology.

[2] Sometimes clouds can be of different colors such as black or white, but overcast usually refers to darker skies.

Periods of overcast weather can range from a few hours to several days.