What Does CAVOK Mean in a METAR or TAF?
CAVOK means ceiling and visibility OK: visibility 10 km or more, no cloud below 5,000 ft, no CB, no significant weather. It stands for Ceiling And Visibility OK.
CAVOK in a real report
EGLL 121750Z 24010KT CAVOK 18/09 Q1022
What it changes for you
CAVOK is a compression. It replaces three groups with one word. Every one of its conditions has to be true before it can be used.
- Visibility 10 kilometres or more
- No cloud below 5,000 feet, or below the highest minimum sector altitude, whichever is greater
- No cumulonimbus or towering cumulus at any level
- No significant weather
The third condition is the one worth noticing. CAVOK rules out a cumulonimbus at any height, not just a low one. That is a stronger claim than the visibility alone.
Where you will see it
Outside the United States, in both METARs and TAFs. US reports use statute miles and never use CAVOK. So the word itself tells you the report is international.
Related codes
Decode a report containing this code
Paste a METAR, TAF, PIREP or SIGMET into the WxDecoder decoder. Every group comes back in plain English. The raw code sits beside it, so you can check the decode rather than trust it.
Frequently asked questions
What does CAVOK mean?
Ceiling and visibility OK. It is a single word replacing the visibility, weather and cloud groups when visibility is 10 km or more, there is no cloud below 5,000 feet or the highest minimum sector altitude, no cumulonimbus at any level, and no significant weather.
Is CAVOK the same as 9999?
No. 9999 reports visibility alone, at 10 km or more. CAVOK makes three claims at once: that visibility, that no significant cloud below the threshold, and no significant weather. CAVOK implies 9999 but 9999 does not imply CAVOK.