What does it mean when a METAR report indicates “CAVOK”?

CAVOK stands for "Ceiling and Visibility OK," which is a term used in aviation weather reports such as METARs. When a report indicates CAVOK, it means that the visibility is good (typically 10 kilometers or more) and that there are no significant meteorological phenomena that could impact flight operations. This also implies that there are no clouds below 5,000 feet, or below the minimums for the airport in question.

This designation is crucial for pilots and air traffic controllers as it signifies that conditions are generally favorable for flying. The presence of CAVOK can also indicate that there are no significant weather conditions like rain, snow, or fog that would interfere with visibility or obstruction to flight.

The other options do not accurately convey the meaning of CAVOK. Clear skies with no clouds, while somewhat close, does not capture the visibility aspect which is also a part of CAVOK. High winds expected or fog and heavy rain present are directly contrary to the notion of CAVOK, as such conditions would indicate a need for caution rather than an assurance of good flying weather.