A line of letters and numbers like 31015G27KT 6000 -SHRA BKN040 can look like gibberish the first time you see it. Yet learning how to read a METAR and TAF quickly becomes second nature once you have a method. It is a skill you will use before every flight, and it is also a source of easy marks in the Meteorology paper of the EASA PPL theory exam. This guide explains every group in order, with decoded examples and the classic exam traps.
A METAR is an observation, a TAF is a forecast. Both are always read in the same order: aerodrome, date and time in UTC, wind (in degrees true and knots), visibility (in metres), present weather, cloud (height in feet above the aerodrome), temperature and dew point, QNH. Learn the CAVOK criteria (10 km, nothing below 5,000 ft, no CB or TCU, no significant weather), the difference between mist (BR) and fog (FG), and the exact meaning of TEMPO, BECMG and PROB. Then practise every day on real reports.
METAR and TAF: What Are They For?
A METAR is an aerodrome’s routine weather observation. It describes the weather actually measured at a specific time, and is typically issued every 30 minutes or every hour depending on the aerodrome. Some are generated by an automatic station: they then carry the word AUTO and only report a limited set of phenomena. Some states also issue SPECI reports, special observations sent between routine METARs when conditions change significantly.
A TAF (Terminal Aerodrome Forecast) describes the conditions expected over a given period. The international format, set by ICAO and the WMO, allows validity periods from 6 to 30 hours:
| Message type | Content | Validity | Issued |
|---|---|---|---|
| METAR | Actual observation | Time of observation (+ 2 h for any trend forecast) | Every 30 or 60 minutes |
| Short TAF | Aerodrome forecast | Less than 12 hours (often 9 h) | Every 3 hours |
| Long TAF | Aerodrome forecast | 12 to 30 hours (often 24 or 30 h) | Every 6 hours |
Your national meteorological provider decides which type each aerodrome gets. When a forecast has to be corrected during its validity, it is reissued as TAF AMD (amended).
The METAR tells you whether you can go now, the TAF whether the weather will hold until you get back.
The Order of Groups: The Key to Reading a METAR
A METAR always follows the same structure. Once you know the order, each group is recognisable by its shape. Here is an example built for practice:
METAR EDFE 191030Z 31015G27KT 280V350 6000 -SHRA SCT025 BKN040 12/08 Q1012 TEMPO 3000 SHRA BKN012
| Group | Meaning |
|---|---|
EDFE | ICAO aerodrome identifier |
191030Z | 19th day of the month, 10:30 UTC (Z = UTC) |
31015G27KT | Wind from 310° true, 15 kt, gusting 27 kt |
280V350 | Direction varying between 280° and 350° |
6000 | Prevailing visibility 6,000 m |
-SHRA | Light rain showers |
SCT025 | Scattered cloud (3 to 4 oktas) at 2,500 ft |
BKN040 | Broken cloud (5 to 7 oktas) at 4,000 ft |
12/08 | Temperature 12 °C, dew point 8 °C |
Q1012 | QNH 1012 hPa |
TEMPO 3000 SHRA BKN012 | Trend: temporarily 3,000 m in moderate rain showers, ceiling 1,200 ft |
Date and Time
The six digits followed by Z give the day of the month, then hours and minutes in UTC. Local time differs from UTC, and the difference usually changes between summer and winter, so always convert carefully. Mixing up UTC and local time is a common error both in the exam and in real flight planning.
Wind
The wind group gives the direction the wind is blowing from, in tens of degrees relative to true north, followed by the mean speed over 10 minutes, in knots (KT). Key rules:
- Gusts (G): reported when the maximum speed exceeds the mean by 10 kt or more.
31015G27KTmeans a mean of 15 kt with gusts to 27 kt. - Variable direction (dddVddd): added when the direction varies by 60° or more (but less than 180°) with a mean speed of 3 kt or more.
- VRB: variable wind with no single direction, usually because it is light (less than 3 kt), or because it varies by 180° or more, for example under a thunderstorm.
- 00000KT: calm.
Some countries outside Europe report speed in metres per second (MPS); within EASA states you will almost always see knots.
Visibility
Visibility is given in metres, as four digits. 9999 means 10 km or more, not “9,999 m”. 0800 means 800 m. When the minimum visibility in one direction is well below the prevailing value (under 1,500 m, or under half the prevailing visibility), it is added with its direction, for example 1400SW. North American reports use statute miles (SM), so don’t let a US example in a textbook confuse you.
At equipped aerodromes you may also see runway visual range (RVR), written like R21/0450N: runway 21, RVR 450 m, no change (N). U means improving, D means deteriorating.
Present Weather
Present weather combines an intensity, a descriptor and a phenomenon. It is the part with the most abbreviations, and so the most exam questions.
| Category | Codes to know |
|---|---|
| Intensity | - light, no sign moderate, + heavy, VC in the vicinity (8 to 16 km) |
| Descriptors | SH showers, TS thunderstorm, FZ freezing (supercooled), BL blowing, DR low drifting, MI shallow, BC patches, PR partial |
| Precipitation | RA rain, DZ drizzle, SN snow, SG snow grains, PL ice pellets, GR hail (5 mm or more), GS small hail or snow pellets |
| Obscuration | BR mist, FG fog, HZ haze, FU smoke, DU dust, SA sand |
| Other | SQ squalls, FC funnel cloud, PO dust whirls, DS and SS duststorm and sandstorm |
Two combinations are red flags for a light aircraft: FZRA (freezing rain, which freezes on contact with the airframe) and FZFG (freezing fog, made of supercooled droplets).
Mist, Fog and Ceiling: The Thresholds to Know by Heart
These numerical definitions are exam favourites.
- BR (mist): visibility between 1,000 m and 5,000 m caused by water droplets.
- FG (fog): visibility below 1,000 m.
- HZ (haze): visibility reduced by dry particles. Like smoke or dust, it is only reported when visibility is 5,000 m or less.
- Ceiling: the height of the base of the lowest cloud layer covering more than half the sky (BKN or OVC), below 20,000 ft.
Cloud amount is expressed in oktas (eighths of the sky):
| Code | Amount | Counts as a ceiling? |
|---|---|---|
FEW | 1 to 2 oktas | No |
SCT | 3 to 4 oktas (scattered) | No |
BKN | 5 to 7 oktas (broken) | Yes |
OVC | 8 oktas (overcast) | Yes |
VV001 | Sky obscured, vertical visibility 100 ft | Yes (treated as one) |
NSC | No significant cloud | No |
NCD | No cloud detected (automatic station) | No |
The height follows the code, in hundreds of feet above the aerodrome: BKN040 means a base 4,000 ft above the field, not 4,000 ft above sea level. Only two cloud types are named: CB (cumulonimbus) and TCU (towering cumulus), for example SCT030CB.
CAVOK: What It Says and What It Doesn’t
CAVOK replaces the visibility, present weather and cloud groups when three conditions are met at the same time:
- visibility of 10 km or more;
- no cloud below 5,000 ft (or below the highest minimum sector altitude, if that is higher) and no CB or TCU;
- no significant weather.
The classic trap: CAVOK does not mean “blue sky”. There may be a layer at 6,000 ft, and nothing is guaranteed along the rest of your route.
Temperature, Dew Point and QNH
The group 12/08 gives the temperature then the dew point, in whole degrees Celsius. A negative value is preceded by M: M02/M05 means −2 °C and −5 °C.
The spread between temperature and dew point tells you a lot:
- a small spread (a few degrees) means the air is close to saturation: the risk of mist or fog increases, especially towards the end of the night with light wind;
- high humidity also favours carburettor icing, even on mild days;
- for convective cloud, a rule of thumb puts the base at roughly 400 ft per degree of spread. With a 5 °C spread you get about 2,000 ft: a useful order of magnitude, not an exact value.
QNH follows the letter Q, in hectopascals, rounded down to the whole hectopascal: Q1012 means 1012 hPa. It is the setting that makes your altimeter read aerodrome elevation on the ground. Reports using inches of mercury use the letter A instead, for example A3005.
TEMPO, BECMG, PROB, FM: Reading the Changes
Change groups appear in a METAR trend forecast (valid for 2 hours) and above all in TAFs. You need to know their exact meaning.
| Group | Meaning | How to use it in flight planning |
|---|---|---|
TEMPO | Temporary fluctuations, each lasting less than 1 h, and less than half the period in total | Be ready to cope with the TEMPO conditions at any time during the period |
BECMG | Lasting change, occurring during the stated period (normally 2 h, never more than 4 h) | After the period, the new conditions replace the old ones |
PROB30 / PROB40 | 30% or 40% probability, alone or combined with TEMPO | A real risk: have a plan B |
⏩ FM | From the stated time, a complete new forecast replaces the previous one | Read it like a new TAF |
NOSIG | No significant change expected in the next 2 h | Only in a METAR trend |
A Decoded TAF Example
Here is a fictitious TAF built for practice:
TAF EDFE 190500Z 1906/2006 24008KT 9999 SCT030 TEMPO 1912/1918 4000 SHRA BKN014 PROB30 TEMPO 1914/1917 TSRA BKN010CB BECMG 2002/2004 3000 BR
Step by step:
- Issued on the 19th at 05:00 UTC, valid from the 19th at 06:00 UTC to the 20th at 06:00 UTC (24 hours).
- Main conditions: wind 240° at 8 kt, visibility 10 km or more, scattered cloud at 3,000 ft.
- Between 12:00 and 18:00 UTC, temporarily: visibility 4,000 m in rain showers, ceiling 1,400 ft.
- Between 14:00 and 17:00 UTC, a 30% probability of temporary thunderstorms with rain and a ceiling of 1,000 ft in cumulonimbus.
- Between 02:00 and 04:00 UTC on the 20th, visibility becomes 3,000 m in mist, and stays that way.
A local flight planned for 15:00 UTC falls right in the TEMPO and PROB30 windows: the morning looks good, but the afternoon calls for real thought, or a postponement.
Decoded METAR Examples, Step by Step
Now let’s read these reports as a pilot planning a flight.
Example 1: METAR EDFE 191030Z 31015G27KT 280V350 6000 -SHRA SCT025 BKN040 12/08 Q1012 TEMPO 3000 SHRA BKN012
- Crosswind: on a runway aligned close to 280°, and ignoring magnetic variation for simplicity, the wind from 310° is 30° off the runway. The crosswind component is half the wind, so about 8 kt, and about 14 kt in the gusts. And because the direction varies up to 350°, the angle can reach 70°: then almost all of the wind becomes crosswind.
- Ceiling: 4,000 ft now, but 1,200 ft temporarily in showers.
- Visibility: 6,000 m, with temporary drops to 3,000 m.
Compare the crosswind with the demonstrated crosswind value in your aircraft’s flight manual. And if the aerodrome is inside a control zone, the Standardised European Rules of the Air (SERA) do not allow a VFR flight to take off or land when the ceiling is below 1,500 ft or ground visibility is below 5 km, unless a special VFR clearance is obtained. The TEMPO conditions cross both thresholds.
Example 2: METAR EDDS 190600Z 00000KT 0300 R25/0450N FG VV001 06/06 Q1024 BECMG FM0730 4000 BR
- Calm wind, visibility 300 m, RVR 450 m on runway 25, no change.
- Fog, sky obscured with a vertical visibility of 100 ft.
- Temperature and dew point identical (6 °C): the air is saturated, which explains the fog.
- From 07:30 UTC, a lasting improvement to 4,000 m in mist: the fog lifts, but conditions remain marginal.
To estimate the crosswind component quickly, learn these approximate values:
| Wind angle to runway | Share of the wind as crosswind |
|---|---|
| 10° | about 1/6 (0.17) |
| 20° | about 1/3 (0.34) |
| 30° | half (0.5) |
| 40° | about 2/3 (0.64) |
| 50° | about 3/4 (0.77) |
| 60° or more | almost all of it (0.87 to 1) |
💡 Tip: every morning, open the METAR and TAF for your home aerodrome and decode them out loud in under a minute, before you look at the sky. After two weeks reading becomes automatic, and you start linking the codes to what you actually see outside.
The Classic EASA PPL Exam Traps
Decoding questions come up regularly in the Meteorology paper. They are rarely hard, but often tricky. These are the most frequent mistakes:
- Mixing up true and magnetic north: METAR and TAF wind is in degrees true; ATIS and tower wind is magnetic.
- Reading a height as an altitude:
BKN015is a base 1,500 ft above the aerodrome, not above mean sea level. - Taking CAVOK for a cloudless sky: there can be cloud above 5,000 ft.
- Reading 9999 as 9,999 m: it means 10 km or more.
- Swapping BR and FG: mist from 1,000 to 5,000 m, fog below 1,000 m.
- Confusing TEMPO and BECMG: one is temporary, the other lasting.
- Forgetting that times are UTC: convert to local time whenever the question requires it.
- Counting SCT as a ceiling: only BKN, OVC (and VV) define a ceiling.
- Missing the M on negative temperatures:
M01means −1 °C.
How to Practise Effectively
Decoding grows through repetition:
- Learn the codes with flashcards: abbreviations, thresholds (BR, FG, CAVOK, gusts) and change groups are perfect for spaced repetition. Ten minutes a day is enough.
- Decode real reports: your home field, the one next door, a cross-country destination. Vary the situations (winter fog, summer thunderstorms, strong wind).
- Do exam-style questions: they get you used to the wording and the traps. With AltiPrep you practise Meteorology questions with an explanation after every answer, and your flashcards come back at the right moment.
- Link the code to the real weather: meteorology makes more sense when you understand why fog forms or why showers come with an unstable air mass. The Meteorology section of our guide to the 9 subjects of the EASA PPL(A) theory exam gives you an overview of the syllabus.
Are You Ready on METARs and TAFs?
| Criterion | Sign that you are ready |
|---|---|
| ⏱ Speed | You decode a full METAR in under a minute |
| Abbreviations | You know every present weather code without hesitating |
| Thresholds | You can recite the criteria for CAVOK, BR, FG and gusts |
| Changes | You can explain the difference between TEMPO, BECMG, PROB and FM |
| Application | You can work out a crosswind component in your head |
From the Report to the Go/No-Go Decision
In the exam, you are asked to decode. In the air, you will be asked to decide. METARs and TAFs are only part of your weather briefing: they describe conditions at an aerodrome, not along the route. For a cross-country flight you also need significant weather charts and upper wind forecasts.
A good habit, encouraged by instructors, is to set your personal minimums: the ceiling, visibility and crosswind below which you will not go, more conservative than the legal minima while you build experience. METARs and TAFs then let you compare actual and forecast weather against those limits in seconds.
These reports support the decision before departure. In flight, your eyes remain your first instrument: if the cloud base comes down faster than forecast, turn back early.
Key Takeaways
- A METAR is an observation, a TAF is a forecast (short TAFs under 12 h, long TAFs up to 30 h).
- Wind is in degrees true and knots, visibility in metres, cloud in feet above the aerodrome.
- CAVOK: 10 km or more, no cloud below 5,000 ft, no CB or TCU, no significant weather.
- BR from 1,000 to 5,000 m, FG below 1,000 m; only BKN and OVC form a ceiling.
- TEMPO is temporary, BECMG lasting, PROB30/40 a risk to plan for, FM a new forecast.
- Decoding one report a day and reviewing the codes with flashcards turns this topic into reliable marks.
Further reading:
- The 9 Subjects of the EASA PPL(A) Theory Exam Explained
- How to Pass the EASA PPL Theory Exam First Time
- Spaced Repetition: The Most Effective Way to Study for Your PPL
Happy studying, and blue skies!
Frequently asked questions
What is the difference between a METAR and a TAF?
A METAR is an observation: it describes the weather actually measured at an aerodrome at a given time. A TAF is an aerodrome forecast, valid for a period of several hours. When planning a flight you read both: the METAR tells you what is happening now, the TAF what is expected while you fly.
What does CAVOK mean in a METAR?
CAVOK means three conditions are met at the same time: visibility of 10 km or more; no cloud below 5,000 ft (or below the highest minimum sector altitude, if that is higher) and no cumulonimbus or towering cumulus; and no significant weather. It does not mean a clear sky, because cloud can still exist above that height.
What is the difference between TEMPO and BECMG in a TAF?
BECMG announces a lasting change: conditions evolve during the stated period and then stay that way. TEMPO announces temporary fluctuations, each lasting less than one hour and covering less than half of the period in total. After a TEMPO spell, the main forecast conditions return.
Is the wind in a METAR given in degrees true or magnetic?
In METARs and TAFs, wind direction is given relative to true north. The wind passed by ATC or broadcast on the ATIS is given relative to magnetic north, like runway numbers. Where magnetic variation is large, the difference matters, and it is a classic exam question.
Where can I get official METARs and TAFs?
Use the official aviation weather service or briefing website of your national meteorological provider or aeronautical information service. Consumer apps are handy for practice, but your preflight planning should rely on official sources.
Is METAR and TAF decoding part of the EASA PPL theory exam?
Yes. Reading coded aerodrome reports and forecasts is part of the Meteorology syllabus of the EASA PPL(A) theoretical knowledge exam, and you need at least 75% on that paper. It is one of the areas where regular practice pays off most quickly.
