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CAVOK stands for "Ceiling and Visibility OK." It is an abbreviation used in some non-U.S. aviation surface weather observation reports (METARs). Information on visibility, runway visual range, present weather and cloud amount, cloud type, and height of cloud base may be replaced in all meteorological reports by the term "CAVOK" when the following conditions apply:

  1. Visibility of 10 km or more, and the lowest visibility is not reported
    (Note 1: In local routine and special reports, visibility refers to the value(s) to be reported in accordance with International Civil Aviation Organization (ICAO) Annexes 3 and; in METARs and SPECIs, visibility refers to the value(s) to be reported in accordance with ICAO Annex 3
    (Note 2: The lowest visibility is reported in accordance with ICAO Annex 3;

  2. No cloud of operational significance; and

  3. No weather of significance to aviation as given in ICAO Annexes 3,, and;

Note that this term is not approved, nor will be used, in the United States.

ICAO, 2007: Meteorological Service for International Air Navigation. Annex 3 to the Convention on International Civil Aviation. 16th ed., International Civil Aviation Organization, 187 pp. Accessed 18 November 2020. Available at

Term edited 30 December 2020.