METAR & TAF Decoder

The FAA handbook’s thunderstorm METAR. METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16 A2992 is station KOKC on the 1st at 1955Z, fully automated. The wind is from 220° true at 15 kt gusting 25, swinging between 180° and 250°. Visibility is 3/4 statute mile, runway 17L has a runway visual range of 2,600 ft, and there is a thunderstorm with heavy rain and mist. The only cloud is an overcast cumulonimbus layer at 1,000 ft, so the ceiling is 1,000 ft. Temperature 18 °C, dew point 16 °C gives a relative humidity of 88.1 %, and 29.92 inHg is 1013.2 hPa.

Its flight category. A 1,000 ft ceiling on its own is MVFR (1,000–3,000 ft), but 3/4 mile is below 1 SM, which is LIFR. The category is the worse of the two: LIFR. The ICAO example 4000 1400SW … BKN025 works the same way: 4,000 m is 2.49 SM, which is IFR, while the 2,500 ft ceiling alone would only be MVFR.

The common mistake: reading a TAF time as a clock time. In FM100100 the first two digits are the day. It means from the 10th at 0100Z, not 10:01, and the FAA’s own key warns that FM100000 is 0000Z on the 10th, not 1000Z. Read the wrong way, a change you expect in the middle of the morning happened more than nine hours earlier, at 0100Z.

METAR and TAF are the code forms written down by the World Meteorological Organization and the International Civil Aviation Organization, so that a pilot can read a report from any airport in the world. ICAO’s Annex 3, the rules for meteorological service to international air navigation, was first published in 1948 and reached its 21st edition in 2025. The WMO’s users’ handbook to the codes, WMO-No. 782, was updated again in 2025 to match Amendment 82 to Annex 3, applicable from 27 November 2025.

Each country may change parts of the code as long as it tells ICAO. The United States kept statute miles for visibility, feet for runway visual range, knots for wind and inches of mercury for the altimeter, which is why a US report says 10SM and A2992 where a European one says 9999 and Q1013. National Weather Service TAFs also leave out BECMG groups and do not use PROB30 in the first nine hours of the forecast.

Many US reports now come from the Automated Surface Observing System. The NOAA, FAA and Defense Department user’s guide of 1998 called ASOS the first system deployed in the modernization of the nation’s weather services, planned for about 1,000 airports. That is where AUTO, AO2, CLR (no cloud detected up to 12,000 ft) and the sensor flags such as FZRANO and TSNO come from.

This decoder reads METAR, SPECI and TAF reports in both US and ICAO form: wind with gusts, VRB and variable sectors in knots or metres per second, visibility in statute miles and fractions or in metres, CAVOK, runway visual range with tendency, present and recent weather, cloud and vertical visibility, NSC and NCD, temperature and dew point, A and Q pressure, ICAO TREND groups, wind shear, and the common US remarks. TAFs are split into their FM, BECMG, TEMPO and PROB periods. It does not fetch anything: you paste the report and it is decoded in your browser.

The codes are decoded as the FAA’s Aviation Weather Handbook (FAA-H-8083-28A, chapters 24 and 27), the Aeronautical Information Manual (7-1-28 and 7-1-29), the WMO’s Aerodrome Reports and Forecasts handbook (WMO-No. 782) and the ASOS User’s Guide define them. National remarks, plain-language notes and groups those documents do not define are shown as not recognised rather than guessed. The flight categories are the ones aviation weather websites use for situational awareness; they are not the VFR weather minimums of 14 CFR 91.155.

Related tools: Crosswind Component Calculator, Density Altitude Calculator and the Dew Point Calculator.

For planning and training only — always use your aircraft’s POH/AFM and official weather and charts.