OpenWeatherMap

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 received from global Meteorological broadcast services and more than 40 000 weather stations.

All weather data can be obtained in JSON, XML or HTML format.

http://openweathermap.org/

For example, you can search weather of London in JSON format with "http://api.openweathermap.org/data/2.5/weather?q=London,uk". The return result will be like this:

{"coord":{"lon":-0.12574,"lat":51.50853},"sys":{"country":"GB","sunrise":1374639224,"sunset":1374696019},"weather":[{"id":803,"main":"Clouds","description":"broken clouds","icon":"04d"}],"base":"gdps stations","main":{"temp":297,"humidity":61,"pressure":1011,"temp_min":295.37,"temp_max":298.71},"wind":{"speed":0.51,"gust":0.51,"deg":199},"clouds":{"all":76},"dt":1374693664,"id":2643743,"name":"London","cod":200}

Examples:
- Parse JSON with Java SE and java-json, to search weather data from OpenWeatherMap.
- Embed OpenWeatherMap in JavaFX WebView
- Another example to embed Open Weather Map in JavaFX WebView