Definition
In a METAR, SKC is the sky condition code reported when no clouds are observed at any level. It is used by a human observer to indicate a completely clear sky.
Plain English
SKC means the observer looked up and saw no clouds anywhere.
Context Anchor
Derivation
SKC is simply a contraction of the words 'sky clear', shortened to fit the compact format of a METAR.
Why Pilots Care
Tells pilots immediately that visual conditions are excellent and no cloud ceilings will affect the flight.
Intuition Check
SKC does not mean all weather is perfect. It only tells you that no clouds were reported; other parts of the report still describe visibility, wind, and other conditions.
Example Sentence 1
The METAR for the destination read SKC, so the pilot expected unrestricted visibility above the airport.
Example Sentence 2
With SKC reported at the destination, we planned a visual approach without needing an instrument procedure.