Learn › How to read a METAR

How to read a METAR

The aviation weather report, decoded one group at a time.

A METAR is the routine weather observation for an airport, issued every 30 or 60 minutes in a compact code that every pilot and controller in the world reads the same way. It looks like a string of gibberish the first time; after ten minutes with this page it reads like a sentence. Here is a typical one:

METAR EGLL 161250Z 24015G28KT 200V280 8000 -RA FEW012 BKN025 13/09 Q1003 TEMPO 4000 RA

The example, decoded

Wind

The first three digits are the direction the wind blows from, in degrees true; the next two or three are the speed, then the unit — KT for knots, MPS for metres per second in some countries. G adds the gust speed. VRB03KT is a light wind of variable direction, and 00000KT is calm. A separate group like 200V280 appears when the direction swings through 60° or more. Note that the tower and the ATIS give wind in degrees magnetic, to match the runway numbers — the METAR does not. The wind decides which runway is in use.

Visibility and runway visual range

Visibility is given in metres, with 9999 meaning 10 km or more. (In the United States it is in statute miles: 10SM.) In poor conditions a runway visual range group appears for each runway — R27L/0800 means 800 m along runway 27L — which is what decides whether an aircraft may start an approach in fog.

Weather

Present weather is a short code built from an optional intensity (- light, + heavy), an optional descriptor and the phenomenon itself. The ones you meet most often:

• Precipitation: RA rain, DZ drizzle, SN snow, GR hail, SHRA rain showers, TSRA a thunderstorm with rain, FZRA freezing rain.
• Obscuration: BR mist, FG fog, HZ haze, DU dust, SA sand, FU smoke.
• Other: SS sandstorm, DS duststorm, SQ squall, VC "in the vicinity" (e.g. VCTS).

Cloud

Cloud groups give the amount in eighths of the sky (oktas) and the base in hundreds of feet above the airfield: FEW 1–2, SCT scattered 3–4, BKN broken 5–7, OVC overcast 8. The lowest broken or overcast layer is the ceiling. A CB or TCU suffix flags cumulonimbus or towering cumulus — convective cloud that pilots avoid. VV002 means the sky is obscured with a vertical visibility of 200 ft, and NSC means no significant cloud.

CAVOK

On a fine day all of the visibility, weather and cloud groups can be replaced by the single word CAVOK — "ceiling and visibility OK": visibility 10 km or more, no cloud below 5,000 ft (or the highest minimum sector altitude, if higher), no cumulonimbus or towering cumulus, and no significant weather.

Temperature, dew point and pressure

13/09 is temperature over dew point in °C; an M means minus (M02/M05). When the two are close together the air is nearly saturated and fog or low cloud is likely. The pressure group is the QNH: Q1003 in hectopascals, or A2992 in inches of mercury in North America — the setting that makes altimeters read altitude above sea level (see flight levels vs altitude).

Trend and remarks

Many METARs end with a two-hour trend: NOSIG (no significant change expected), BECMG (becoming — a lasting change) or TEMPO (temporary fluctuations). American reports add a RMK section with extra detail such as precise temperature and sea-level pressure.

METAR, SPECI and TAF

A METAR is an observation — what the weather is now. A TAF (terminal aerodrome forecast) uses the same codes to say what the weather will be over the next 9 to 30 hours, with groups such as FM (from), BECMG, TEMPO and PROB30. Crews plan with the TAF and fly with the latest METAR.

Try it on live weather

The site's Aviation Weather page shows the live METAR and TAF for any airport, decoded into plain English with a wind dial and the crosswind on each runway — a perfect way to practise. Then take the controller's seat in the ATC Radar Simulator and pick the runway the wind would give you.