How to use
- Copy a METAR or SPECI report, for example from a flight planning app, and paste it into the box.
- Read the decoded lines. Groups after a trend word such as TEMPO or BECMG are marked as part of the trend.
- Anything the decoder does not recognise is listed as “Not decoded”, so nothing is silently lost.
How a METAR is built
The groups always come in the same order:
| Group | Example | Meaning |
|---|---|---|
| Station and time | KJFK 041251Z | airport, day 4 at 12:51 UTC |
| Wind | 31012G20KT | from 310° at 12 kt, gusts 20 kt |
| Visibility | 9999 or 10SM | 10 km or more, or 10 statute miles |
| Weather | -RA, +TSRA, BR | light rain, heavy thunderstorm with rain, mist |
| Clouds | FEW035, BKN250 | few at 3,500 ft, broken at 25,000 ft |
| Temperature / dew point | 12/M02 | 12 °C, dew point −2 °C (M means minus) |
| Pressure | Q1013 or A3012 | QNH 1013 hPa, or 30.12 inHg |
| Trend | NOSIG, TEMPO, BECMG | forecast for the next two hours |
Weather groups are shown as a list - intensity, descriptor and phenomenon - so “-SHRA” reads “light, showers, rain”.
Worked example
The sample report decodes as:
- METAR — routine report from KJFK, day 4 of the month, 12:51 UTC;
- wind from 310° at 12 kt (22 km/h), gusts 20 kt (37 km/h), direction between 280° and 340°;
- visibility 10 statute miles (16.1 km);
- -RA: light, rain;
- Few (1–2 oktas) at 3,500 ft (1,067 m) and Broken (5–7 oktas) at 25,000 ft (7,620 m);
- temperature 12 °C (54 °F), dew point -2 °C (28 °F);
- altimeter 30.12 inHg (1,020 hPa);
- NOSIG — no significant change expected in the next 2 hours;
- remarks AO2 SLP199, shown as they are.
Tips
- Conversions are rounded: km/h and knots to whole numbers, statute miles to a tenth of a kilometre, hPa to a whole number.
- Check the time: a METAR is an observation, not a forecast, and an hour-old report may already be out of date.
- For takeoff and landing planning use the official briefing; this decoder is for reading and learning the code.