Cloud Cover—What It Means

It’s common to read or hear in weather forecasts the terms clear, scattered, broken, or overcast. While these terms may sound subjective, they are actually defined explicitly by the National Weather Service. Sky cover is categorized by the amount of sky obscured by opaque clouds, measured in oktas, or eighths of the sky. Thin and wispy are separate definitions that can still be used in the weather report, i.e., "thin overcast", or "thin, high wispy cirrus". With that in mind, here are the basic definitions.

Clear (CLR)—clear skies mean no clouds, 0/8 or zero oktas.

Clear skies, Eleven Mile State Park, CO (Keith Thompson).

Scattered (SCT) — clouds cover 3/8 to 4/8 of the sky (3 to 4 oktas). This is also referred to as partly cloudy; clouds are present, but there is more clear sky than cloud.

Scattered clouds, Taylor Park, CO (Keith Thompson).

Broken (BKN) — clouds cover 5/8 to 7/8 (5 to 7 oktas) of the sky. The sky is more cloud-covered than clear, but is not completely overcast.

Broken clouds, Cumberland Pass, CO (Keith Thompson).

Overcast (OVC) — clouds cover 8/8 (8 oktas) of the sky. No clear sky is visible.

Overcast sky, Colorado Springs (Keith Thompson).

Here is the complete sky cover scale:

Sky Condition	Coverage in Oktas	NWS Abbrev.
Clear	0/8	SKC or CLR
Few	1/8- 2/8	FEW
Scattered	3/8 - 4/8	SCT
Broken	5/8 - 7/8	BKN
Overcast	8/8	OVC