Broken clouds

Broken clouds are a cloud layer covering five eighths to seven eighths of the sky. In a METAR, broken coverage is coded BKN followed by the cloud base height in hundreds of feet above the station. A broken layer establishes a ceiling for aviation weather purposes.

How it works

Cloud coverage is estimated across the sky dome above the observing station. A group such as BKN020 means broken clouds with a base at 2,000 ft above the station. The report may include multiple layers, and the lowest broken or overcast layer controls the reported ceiling.

Broken clouds differ from scattered clouds. SCT represents three eighths to four eighths coverage and does not establish a ceiling. Overcast, coded OVC, represents seven eighths to eight eighths coverage and also establishes a ceiling.

Example

A report contains SCT015 BKN030. The scattered layer begins at 1,500 ft, but the broken layer at 3,000 ft establishes the ceiling. If the lower layer becomes broken in a later observation, the reported ceiling changes to that lower base.

Why it matters

Broken cloud coverage can affect visual references, traffic pattern visibility, and the weather category used for planning. The reported base is an observation at one station and time. It does not describe the top of the clouds or guarantee conditions along a route.

Read the full METAR, including its observation time and visibility, then compare it with the TAF. Use current official weather data for actual planning.

Related terms and tools

• Ceiling
• Overcast
• METAR