OpenWeatherMap has its own model of weather calculation. For some regions we leverage WRF model. The data for calculations itself is provided by the global meteorological centers, environmental organizations, airports and others. We are open for cooperation with local weather data providers and owners of weather stations so as to provide our users with the most accurate weather data possible.
NOAA http://www.noaa.gov/
Environment Canada http://www.weatheroffice.gc.ca
European Centre for Medium-Range Weather Forecasts (ECMWF) http://www.ecmwf.int/
気象庁 Japan Meteorological Agency http://www.jma.go.jp
METAR data from airports http://en.wikipedia.org/wiki/METAR
APRS network http://www.aprs-is.net/
Private weather stations. We have more than 40,000 stations in our system. Connect your weather station to OpenWeatherMap today.