|Examples of METAR reports.|
METAR - Aviation routine weather report - An hourly report of the weather, METAR is the international standard code format for hourly surface weather observations. In the U.S., METAR reports are taken once an hour between 50 minutes past the hour and the top of the (next) hour. In addition, observations taken due to changing conditions, known as SPECI reports, are also recorded.
Most METAR observations are made at an aerodrome. METAR observations are coded using a standard format based on a mix of English and French words (e.g., GR for hail or FU for smoke are based on French words, but the international abbreviations for Fog and Rain are FG and RA respectively).
The U.S. had been reporting weather in a standardized "SA" format since the 1960's.
In July 1993, the U.S. completed Phase 1 of their conversion to METAR when they began converting SA formatted products to METAR for international dissemination.
On January 1, 1996, the NWS converted to the new international METAR format for international dissemination and to the new international TAF format at 90 locations. On February 1, 1996, TAF formatted forecasts issued for an additional 12 airport locations were instituted. The NWS completely converted to the new METAR/TAF code formats for domestic dissemination beginning at 0800 hours UTC on July 1, 1996. At that time, SAs and FTs were replaced with METARs and TAFs, and SAs and FTs were discontinued.
The name METAR is commonly believed to have its origins in the French phrase message d’observation météorologique pour l’aviation régulière ("Meteorological observation message for routine aviation") and would therefore be a contraction of MÉTéorologique Aviation Régulière. The AIM states the definition as aviation routine weather report while the international authority for the code form, the WMO, holds the definition to be aerodrome routine meteorological report.