METAR decoder
Paste a raw METAR below and it is translated element by element: wind direction and speed, visibility, present weather, cloud layers with bases, temperature and dew point, QNH and the resulting flight rules category. Everything runs in your browser — nothing is sent anywhere.
Decoded report
A worked example, element by element
Take LEMD 211200Z 24008KT 9999 FEW045 28/12 Q1018 NOSIG. The station is Madrid-Barajas; the observation was taken on the 21st at 12:00 UTC. Wind blows from 240° true at 8 knots — light, and nearly aligned with Barajas' south-westerly runways. 9999 means visibility of 10 km or more. The only cloud is a few at 4,500 ft above the field, nowhere near a ceiling. Temperature 28 °C against a dew point of 12 °C — a dry 16-degree spread, so no fog risk as evening cools. QNH 1018 hPa goes straight into the altimeter, and NOSIG promises no significant change in the next two hours. Verdict: solid VFR.
Now paste the same line into the decoder above and compare against your own reading — that round trip, repeated with reports from airports you know, is the fastest way to make the format automatic.
The abbreviations that carry the weather
Present-weather groups compress a lot into two-letter pairs: RA rain, SN snow, FG fog, BR mist, TS thunderstorm, SH showers, with + and - marking intensity and VC meaning «in the vicinity». Cloud amounts come in oktas: FEW one to two, SCT three to four, BKN five to seven — the first broken layer sets the ceiling — and OVC a full eight. The decoder expands all of them, but knowing the common ones by sight makes the raw line readable at a glance.
How to read a METAR
A METAR follows a fixed element order: station identifier, observation day and time (UTC), wind, visibility, present weather, clouds, temperature/dew point, and pressure. Two details trip up most readers: wind is given in degrees true from which the wind blows, and cloud bases are heights above aerodrome level in hundreds of feet — BKN015 is a broken layer at 1,500 ft.
Flight rules follow from the two limiting values: category drops to IFR below 1,000 ft ceiling or 3 statute miles visibility, and to LIFR below 500 ft or 1 mile.
Frequently asked questions about the decoder
Does the decoder send my report anywhere?
No — decoding runs entirely in your browser in plain JavaScript. Nothing is transmitted, stored or logged, which also makes the tool usable offline once the page has loaded.
Which METAR elements does it understand?
Station, time, wind with gusts and variable groups, visibility in metres or statute miles, present weather, cloud layers with CB/TCU markers, temperature and dew point, QNH in hectopascals or inches — plus the flight rules category derived from ceiling and visibility.
Can it decode TAF forecasts too?
The decoder focuses on observations. TAFs use the same element codes though, so once METARs read fluently, a TAF is the same vocabulary with BECMG and TEMPO change groups around it — both shown live on every station page.
Why does my report fail to decode?
Usually a truncated line — copy the full report from the first group to the end. Military and unusual regional formats can carry non-standard groups; the decoder reads the standard elements and skips what it cannot identify.