Weather stations from around the world report weather conditions every hour using the WMO approved METAR format (see WMO code manual FM-15 and FM-16). These data are centrally collected by each country and distributed internationally by WMO and other services. ADDS gets its data a variety of feeds provided by NWS.
ADDS decodes the METAR reports and saves up to seven days of data in a database. The data available in the database includes: temperature, dew point, wind speed, wind direction, visibility, clouds and ceiling, and any reported weather conditions.