METAR is a format for reporting weather information. A METAR weather report is predominantly used by pilots in fulfillment of a part of a pre-flight weather briefing, and by meteorologists, who use aggregated METAR information to assist in weather forecasting.
Raw METAR is the most popular format in the world for the transmission of weather data. It is highly standardized through International Civil Aviation Organization (ICAO), which allows it to be understood throughout most of the world.
Read more about METAR: Origin, History, Naming, Information Contained in A METAR, Regulation, METAR Conventions, Cloud Reporting, Flight Categories, US METAR Abbreviations