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Learning hub · Meteorology · Lesson 3

Reading a METAR and a TAF

A METAR is what the weather is doing now at an aerodrome. A TAF is what it is expected to do. Both are written in a fixed order, so once you know the order you can read any of them, anywhere in the world.

About 13 minutes, plus the quiz. Part of Meteorology. It builds on Clouds, stability and fronts.

1. The order of a METAR

A METAR is a routine observation, usually issued every 30 minutes or every hour. Time is always UTC. The groups come in the same order every time, and a group that does not apply is left out.

  • Station and time: the four-letter ICAO code, then day and time, for example 261050Z is the 26th at 1050 UTC.
  • Wind: three digits for the direction the wind blows from, in degrees true, then the speed, then KT. 24012G22KT is from 240°, 12 kt, gusting 22. VRB means variable. A group such as 200V270 gives the range when the direction varies. Some countries report speed in metres per second (MPS). The wind you hear from a tower or ATIS is given in degrees magnetic, so it differs from the METAR by the local variation.
  • Visibility: in metres. 8000 is 8 km, 0800 is 800 m, and 9999 means 10 km or more.
  • CAVOK (said “cav-oh-kay”) replaces visibility, weather and cloud together when visibility is 10 km or more, there is no cloud below 5,000 ft (or below the highest minimum sector altitude, if that is higher), no cumulonimbus or towering cumulus, and no significant weather. It is a good sign, but read the wind and the QNH too.
  • Present weather: codes, with - for light and + for heavy. RA rain, DZ drizzle, SN snow, SH shower, TS thunderstorm, FG fog, BR mist, HZ haze, FZ freezing. They combine: -SHRA is light rain showers, +TSRA is a thunderstorm with heavy rain.
  • Cloud: amount and height. FEW is 1 to 2 oktas (eighths of the sky), SCT 3 to 4, BKN 5 to 7, OVC 8. The height is in hundreds of feet above the aerodrome, so BKN025 is broken at 2,500 ft. CB or TCU after the height names the type. The lowest layer of BKN or OVC is often called the ceiling.
  • Temperature and dew point: in °C, with M for minus. 14/12 is 14°C and 12°C; 04/M01 is 4°C and −1°C.
  • Pressure: Q then the QNH in hectopascals. Q1008 is 1008 hPa. Compare Pressure, QNH and the altimeter.
  • TREND: a short forecast for the next two hours. NOSIG means no significant change; BECMG and TEMPO introduce a change.

2. The TAF: a forecast with a time frame

A TAF uses the same codes, so the weather groups are familiar. What is new is time. After the station comes the issue time, then the validity period, written as two day-and-hour pairs: 2606/2706 means from 0600 UTC on the 26th until 0600 UTC on the 27th. The length depends on the aerodrome, so look at the dates rather than assume.

The first lines give the expected weather at the start. Changes are marked by keywords.

  • BECMG (becoming): a lasting change, happening gradually inside the period given, for example BECMG 2610/2612. After it, the new conditions apply.
  • TEMPO (temporary): short fluctuations. Each one lasts less than an hour and together they cover less than half of the period they apply to. Afterwards the earlier conditions return.
  • PROB30 and PROB40: a 30 or 40 per cent chance of the weather that follows. Lower or higher chances are not forecast this way.
  • FM (from): a complete change of the forecast from the time given.

A TAF is a forecast of the weather over the aerodrome and its immediate surroundings. It can be wrong, and it is out of date as soon as the next one is issued. Always read it with the latest METAR.

3. Decoding two invented reports

Both reports below are invented for this lesson, for a made-up aerodrome with the code LRZZ.

METAR LRZZ 261050Z 24012G22KT 200V270 8000 -RA SCT015 BKN025 14/12 Q1008 BECMG 5000 BKN010=

  1. LRZZ 261050Z: the aerodrome, the 26th, 1050 UTC.
  2. 24012G22KT 200V270: wind from 240° true at 12 kt, gusting 22 kt, direction varying between 200° and 270°.
  3. 8000 -RA: visibility 8 km in light rain.
  4. SCT015 BKN025: scattered cloud at 1,500 ft, broken at 2,500 ft. The ceiling is 2,500 ft.
  5. 14/12: temperature 14°C, dew point 12°C. The spread is only 2°C, so low cloud and mist are close.
  6. Q1008: QNH 1008 hPa.
  7. BECMG 5000 BKN010: in the next two hours it is expected to become gradually 5 km with broken cloud at 1,000 ft. This is a worsening trend.

TAF LRZZ 260500Z 2606/2706 25010KT 9999 SCT030 BECMG 2610/2612 28018G30KT TEMPO 2612/2618 4000 SHRA BKN012CB=

From 0600 UTC on the 26th, wind from 250° at 10 kt, visibility 10 km or more, scattered cloud at 3,000 ft. Gradually between 1000 and 1200 UTC the wind becomes 280° at 18 kt gusting 30. From 1200 to 1800 UTC there will be short spells of 4,000 m visibility in rain showers, with broken cumulonimbus at 1,200 ft. The cumulonimbus is the important part of this forecast: see Thunderstorms, icing and turbulence.

The VectorEFB guide How to read a METAR and TAF goes through the same codes with more examples.

4. Using them well

  • Read the whole report, not just the cloud and visibility. Wind, gusts and the temperature and dew point spread often matter more.
  • Compare the TAF with the latest METAR. If the METAR is already worse than the TAF said it would be, trust the METAR and doubt the rest of the forecast.
  • Check the validity times of the TAF against your planned flight, and your alternate.
  • Reports are issued in several formats around the world. Some countries add groups that are not in this lesson, such as RMK remarks. If a group is unfamiliar, look it up.

This lesson is for learning the code. For a real flight, use the official, current reports and forecasts from your national meteorological service or your briefing system, and the AIP.

5. Try it yourself

Work each one out on paper first, then open the answer to compare. The numbers are invented.

  1. Decode this invented METAR: LRZZ 270720Z VRB03KT 1200 BR OVC004 06/05 Q1021 NOSIG. Give the wind, the visibility, the cloud and the QNH, and say whether you would expect a VFR flight to be possible. Why is NOSIG not much comfort?
    Show the answer

    Wind variable at 3 kt. Visibility 1,200 m in mist (BR). Overcast at 400 ft, which is also the ceiling. Temperature 6°C, dew point 5°C, QNH 1021 hPa. NOSIG means no significant change in the next two hours.

    With a 400 ft ceiling and 1.2 km visibility, VFR flight is not realistic for a student pilot. NOSIG means the poor weather is expected to stay, so waiting two hours will probably not help. The spread is 1°C, so the mist could even thicken into fog.

  2. Decode this invented TAF line and say when each part applies: TAF LRZZ 271100Z 2712/2812 18008KT CAVOK TEMPO 2714/2718 5000 TSRA BKN020CB PROB30 2800/2804 3000 BR.
    Show the answer

    Valid from 1200 UTC on the 27th to 1200 UTC on the 28th. Base forecast: wind from 180° at 8 kt, CAVOK.

    TEMPO 2714/2718: between 1400 and 1800 UTC on the 27th, short spells of 5 km visibility with a thunderstorm and rain, and broken cumulonimbus at 2,000 ft. Each spell is under an hour.

    PROB30 2800/2804: a 30 per cent chance, between 0000 and 0400 UTC on the 28th, of 3,000 m visibility in mist.

    Planning point: do not fly that afternoon on the strength of the CAVOK at the top. The thunderstorm is the headline.

  3. Write the following in METAR code: wind from 090° at 15 kt gusting 25 kt; visibility 6 km; light drizzle; few clouds at 800 ft and broken at 3,000 ft; temperature 9°C, dew point 8°C; QNH 997 hPa.
    Show the answer

    Wind: 09015G25KT. Visibility 6 km is 6000. Light drizzle: -DZ. Cloud: FEW008 BKN030. Temperature and dew point: 09/08. Pressure: Q0997 (four digits, so a leading zero).

    Together: 09015G25KT 6000 -DZ FEW008 BKN030 09/08 Q0997. Check: direction is three digits, speed two, and the cloud heights are in hundreds of feet.

6. Watch

A walk through the METAR groups in order. This video is American, so wording and some rules differ from European (ICAO/EASA) practice: for example, American METARs give visibility in statute miles and pressure in inches of mercury. The order of the groups is the same idea you learned above.

Open on YouTube if the player does not load. Not made by VectorEFB; check what you learn against your flying school’s material and your instructor.

More to watch

A second explanation of METAR and TAF decoding, from a different channel. Check what you learn against the ICAO format used in your own country.

Open on YouTube if the player does not load. Not made by VectorEFB.

7. Check yourself

Five original practice questions. Answer them, press Check answers and read each explanation.

1. What does the group 24012G22KT tell you?

The first three digits are the direction the wind comes from, in degrees true. Then 12 kt, and G22 is the gust speed.

2. Which set of conditions allows CAVOK?

CAVOK needs all three together. Any significant weather or low cloud rules it out.

3. A METAR reports BKN012. What does it mean?

BKN is five to seven oktas. The height is in hundreds of feet, so 012 is 1,200 ft.

4. In a TAF, what does TEMPO mean?

TEMPO covers temporary changes. BECMG is the lasting, gradual change, and PROB gives a chance.

5. A METAR has temperature and dew point 05/M02 and Q1031. What is the QNH?

Q is followed by the QNH in hectopascals. The dew point is minus 2°C, but that is a separate group.

Next: Thunderstorms, icing and turbulence. Back to the learning hub.

For training and situational awareness only. Not certified for navigation. Always use official charts, the AIP, NOTAMs and a proper weather briefing for real flights.