Definition
Meteorological Aerodrome Report (METAR), also known as Meteorological Terminal Aviation Routine Weather Report, Meteorological Terminal Air Report or Meteorological Airfield Report is a format for reporting weather information.
The World Meteorological Organisation (WMO) describes METAR as the aerodrome routine meteorological report.
The US Federal Aviation Administration (FAA), the US National Oceanic and Atmospheric Administration (NOAA), and the UK Met Office all describe a METAR as aviation weather report.
Discussion
The elements of these messages are normally given in the order below. Some elements or groups may be omitted when they are not needed or do not apply:
Code Name
The indicator group e.g. METAR, SPECI, or TREND as appropriate. Where a number of METARs are issued in the same bulletin, this, along with a date time group may be in the bulletin header.
Location
The ICAO indicator of the reporting station eg. EGLL.