What does CAVOK mean?

CAVOK (Ceiling And Visibility OK) replaces the visibility, weather and cloud groups when visibility is 10 km or more, there is no significant cloud below 5,000 ft (or the highest minimum sector altitude), and no significant weather.

Why is the wind direction sometimes 'true' but the tower gives me 'magnetic'?

METAR and TAF winds are referenced to true north. ATIS broadcasts and tower-passed winds are referenced to magnetic north so they align with the runway designators you use.

How to Read a METAR

Key takeaways

A METAR is read left to right as a fixed sequence of groups.

Wind is given as direction (true) and speed, with gusts after a G.

Visibility, weather and cloud follow, then temperature, dew point and pressure.

Always check the issue time and whether the report is an AUTO or corrected (COR) observation.

What is a METAR?

A METAR (Meteorological Aerodrome Report) is a routine, coded observation of the weather at an aerodrome, normally issued every half hour or hour. It describes conditions at the moment of observation — it is not a forecast.Because the format is standardised by ICAO, a METAR from London reads the same way as one from Lisbon or Los Angeles. Learn the sequence once and you can decode any of them.

The standard sequence

Every METAR follows the same order: station identifier, day and time, wind, visibility, present weather, cloud, temperature and dew point, then pressure (QNH), followed by any supplementary information and remarks.Reading strictly left to right keeps you from misinterpreting a group — each position has a defined meaning.

Wind and visibility

Wind is reported as a three-figure direction in degrees true, followed by the speed, e.g. 24015KT means from 240 degrees at 15 knots. Gusts are appended after a G, and VRB indicates variable direction.Visibility follows in metres (or statute miles in the US). 9999 means 10 km or more; CAVOK replaces visibility, weather and cloud when conditions are good.

Cloud, temperature and pressure

Cloud is reported in oktas as FEW, SCT, BKN or OVC with a height in hundreds of feet above aerodrome level. Temperature and dew point follow in degrees Celsius, with an M prefix for negative values.Finally, the pressure setting (QNH) is given — Q for hectopascals (Q1013) or A for inches of mercury (A2992).

Frequently asked questions

No. A METAR describes observed conditions at the time of the report. For a forecast of how conditions will change, read the TAF (Terminal Aerodrome Forecast).

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