The OpenWeatherMap service provides free weather data and forecast API suitable for any cartographic services like web and smartphones applications. Ideology is inspired by OpenStreetMap and Wikipedia that make information free and available for everybody.
OpenWeatherMap provides wide range of weather data such as map with current weather, week forecast, precipitation, wind, clouds, data from weather stations and many others. Weather data is recieved from global meterological broadcast services and more than 40 000 weather stations.
You can recieve any weather data for your application by using JSON / XML API. Lots of applications for Android and iOS use OpenWeatherMap as weather data source. By the way the data can be received from WMS server and can be embedded into any cartographic web-application.
License: Creative Commons 2.0 License