I’ve mentioned a few resources for those developing weather apps such as the beautiful Sol example app.
Here’s an open source library from Rain called SmileWeather that allows you search & parse a wide variety of weather data, and also provides a weather widget style user interface.
SmileWeather downloads weather from Wunderground & OpenWeathermap with virtually ever weather detail you could possibly want. Both services offer a free tier for building and testing your apps.
Here is an image from the readme showing the SmileWeather weather widget in action:
You can find SmileWeather on Github here.
A great library for creating weather maps.