Weather terms for cloudiness

As an aid to weather forecasting to determine cloudiness The National Weather Service uses these terms to define these sky conditions:

Sky Condition Opaque Cloud Coverage
Clear/Sunny 1/8 or less
Mostly Clear/Mostly Sunny 1/8 to 3/8
Partly Cloudy/Partly Sunny 3/8 to 5/8
Mostly Cloudy 5/8 to 7/8
Cloudy 7/8 to 8/8

For more weather terms see Forecast Terms at theĀ  National Weather Service.