A third party World Weather Online Java library is available on Github. Author Raúl Raja Martínez guides developers through downloads and usage. The downloads section includes maven dependency and the usage part includes parameters, API Key, numberOfDays, and query. Android developers can benefit from this third party library due to the integration of weather services in mobile apps.
Popular weather data site Weather Underground (Wunderground) has a new version of its Weather Underground API and two things are notable: its former XML service is being phased out in favor of JSON. And it has a very clear pricing structure, though there's a free version for non-commercial projects.