How to read a METAR: a complete guide for student pilots

What is a METAR?

A METAR is an observation of current weather at an airport, issued every 30 or 60 minutes. It is produced by automated sensors or a human observer, and follows a fixed ICAO format recognised worldwide. A SPECI is a special METAR issued outside the routine schedule when weather changes rapidly.

METARs are the primary go/no-go decision tool for VFR pilots. Reading one correctly could save your life.

The METAR format: an overview

A typical METAR looks like this:

EHAM 191155Z 22015KT 9999 FEW025 BKN060 14/07 Q1012 NOSIG

Each space-separated group encodes a specific piece of information. Let's decode it section by section.

Station identifier and time

EHAM is the ICAO code for Amsterdam Schiphol Airport. 191155Z means the 19th of the month at 11:55 UTC (Z = Zulu = UTC). Always convert to local time for your flight planning, but file and brief in UTC.

Wind

22015KT means wind from 220° (SW) at 15 knots. If the wind is variable, it reads VRB03KT. A gust is shown as 22015G25KT (gusting to 25 kt). When the variation in direction is large, you may see 220V270: meaning the wind is varying between 220° and 270°.

For runway planning: subtract the runway heading from the wind direction to find the crosswind component. UP Aviation's METAR decoder shows you the crosswind limit bar automatically.

Visibility

9999 means 10 km or more: the maximum reportable. In Europe, visibility is in metres (e.g. 4000 = 4 km). In the US, it is in statute miles (e.g. 3SM). Values below 5 km indicate reduced visibility and affect your VFR legality.

Modifiers: CAVOK (Ceiling And Visibility OK) replaces visibility and cloud groups when visibility ≥ 10 km, no cloud below 5000 ft and no significant weather.

Present weather

Present weather codes appear between visibility and cloud groups. Common ones:

• RA = rain, DZ = drizzle, SN = snow, GR = hail • TS = thunderstorm, FG = fog, BR = mist, HZ = haze • FZ prefix = freezing (FZRA = freezing rain) • + or − prefix = heavy or light (−RA = light rain, +TSRA = heavy thunderstorm with rain)

If no weather is present, this group is omitted.

Cloud cover

Cloud groups use FEW (1–2 oktas), SCT (3–4 oktas), BKN (5–7 oktas) or OVC (8 oktas), followed by height in hundreds of feet AAL (Above Aerodrome Level). FEW025 = few clouds at 2500 ft. BKN060 = broken layer at 6000 ft.

SPECIAL: CB (cumulonimbus) or TCU (towering cumulus) are always added when present: BKN020CB. These are hard limits for VFR: never enter or fly under a CB.

Temperature and dew point

14/07 means temperature 14°C, dew point 7°C. When the spread (T − Td) is less than 3°C, fog or low cloud formation is likely. When both values approach 0°C, icing risk increases rapidly.

A useful derived value: the Lifted Condensation Level (LCL), which approximates the cloud base: LCL (ft) ≈ (T − Td) ÷ 2.5 × 1000. So 14 − 7 = 7 ÷ 2.5 × 1000 = ~2800 ft: consistent with the FEW025 in our example.

QNH

Q1012 is the QNH: the altimeter setting that makes your altimeter read true altitude above sea level when on the ground. Set this on your altimeter before every flight. In the US, the format is A2992 (inches of mercury, not hPa).

Trend forecast (NOSIG, TEMPO, BECMG)

The final group is a short 2-hour trend forecast appended to the METAR:

• NOSIG = no significant change expected • TEMPO = temporary fluctuation (less than 1 hour at a time) • BECMG = becoming (a gradual change expected within 2 hours)

For example: BECMG 4000 BR means visibility expected to drop to 4 km with mist within 2 hours.

Practice with real METARs

Theory only takes you so far: real proficiency comes from reading live METARs daily. Use UP Aviation's free METAR & TAF decoder: type any ICAO code and get a fully decoded report with colour-coded sky cross-section, wind compass, visibility sparkline and runway crosswind bar. It is free, works on any device, and shows real-time data from aviationweather.gov.