A METAR is a routine surface weather observation, normally issued every hour; a SPECI is a special report issued when conditions change significantly. Groups always appear in the same order:
| Group |
Example |
Meaning |
| Station and time |
KJFK 260351Z |
JFK, the 26th at 03:51 UTC |
| Wind |
02022G31KT |
From 020° true at 22 knots, gusting to 31 |
| Visibility |
10SM, 1 1/2SM, 9999 |
Statute miles in the US, meters elsewhere (9999 = 10 km or more) |
| Weather |
-RA BR, +TSRA, VCSH |
Light rain and mist; heavy thunderstorm with rain; showers in the vicinity |
| Sky |
FEW060 BKN095 OVC110 |
Cloud amount and height in hundreds of feet above ground |
| Temperature/dewpoint |
14/09, M02/M05 |
°C; M means minus |
| Altimeter |
A2991, Q1013 |
29.91 inHg; 1013 hPa |
| Remarks |
RMK AO2 SLP128 T01440089 |
Automated station type, sea-level pressure, precise temperatures |
The ceiling is the lowest broken (BKN) or overcast (OVC) layer, or the vertical visibility (VV) into an obscuration. With visibility, it sets the flight category shown on the decoded report.
How the decoder was checked
The decoder was compared with the Aviation Weather Center's own parser on 1,500 real reports from around the world, taken from its public data cache on September 26, 2026, including every report in that cache that was not VFR. On every well-formed report the two agree on station, wind, visibility, temperature, dewpoint, altimeter, cloud layers with a reported height, and flight category. The only differences are deliberate:
- when a report's visibility is missing (
////), the Aviation Weather Center substitutes the runway visual range, while this decoder reports visibility as not available;
- where a station sends two altimeter groups that disagree, both are shown.
Groups it cannot recognize are highlighted rather than guessed. A handful of malformed reports in the sample had them.
US remarks carry some of the most useful information, and the decoder expands the common codes:
- AO1/AO2: automated station without or with a precipitation sensor that can tell rain from snow.
- SLP128: sea-level pressure 1012.8 hPa.
- T01440089: temperature 14.4 °C and dewpoint 8.9 °C, to a tenth of a degree.
- P0001: 0.01 inch of precipitation in the last hour.
- PK WND 03034/0301: peak wind 34 knots from 030° at 03:01.
- RAB20E45: rain began at 20 past and ended at 45 past the hour.
- $: the station needs maintenance.
Lightning, virga and cumulonimbus locations, wind shifts, variable ceilings and visibility, pressure tendencies and the Canadian cloud-opacity remarks are decoded too. Plain-language remarks are kept as written.
Using it for flight planning
A decoded METAR is a snapshot of the past hour at one airport. Before flight, get a complete briefing from an approved source; in the United States that is Flight Service or an FAA-accepted provider. Check the TAF for what is expected next, and run the reported wind through the crosswind calculator.
Questions pilots ask
How do you read a METAR?
In order: report type, station, day and time in UTC, wind, visibility, weather, sky condition, temperature and dewpoint, altimeter setting, then remarks after RMK. The decoder explains each group in that order and flags anything it does not recognize.
Are METAR winds true or magnetic?
True. METAR and TAF wind directions are relative to true north, while ATIS, AWOS broadcasts and tower winds are magnetic like the runway numbers.
What do VFR, MVFR, IFR and LIFR mean?
They are flight categories. VFR: ceiling above 3,000 feet and visibility above 5 miles. Marginal VFR: ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 miles. IFR: ceiling 500 to below 1,000 feet and/or visibility 1 to below 3 miles. Low IFR: ceiling below 500 feet and/or visibility below 1 mile.
Where does the live METAR come from?
From the Aviation Weather Center's public data service at aviationweather.gov, fetched through this site and cached for five minutes. For flight, get an official briefing; a decoded report is a study and planning aid.
Does it decode international METARs?
Yes: meter visibility, CAVOK, QNH in hectopascals, winds in meters per second, runway visual range, recent weather, trend forecasts such as NOSIG and TEMPO, and military color states.