yahoo-weather-java-api 
Current version is not working because the yql service by Yahoo has been dismissed (https://developer.yahoo.com/yql/)
A Java library for the yahoo weather service.
The library is a lightweight wrapper for the Yahoo Weather API (http://developer.yahoo.com/weather/).
The only required dependency is the slf4j-api library.
Usage example:
YahooWeatherService service = new YahooWeatherService();
Channel channel = service.getForecast("2502265", DegreeUnit.CELSIUS);
System.out.println(channel.getDescription());
Dependency declaration:
<dependency>
<groupId>com.github.fedy2</groupId>
<artifactId>yahoo-weather-java-api</artifactId>
<version>2.0.2</version>
</dependency>
Changelog:
* 2.0.2 Fixes time parsing when minutes are not padded.
* 2.0.1 Fixes RFC822 date parsing. Fixed lastBuildDate field parsing.
* 2.0.0 Changed whole implementation to use YQL for querying
* 1.2.0 YahooWeatherService constructor now accepts a Proxy to be used during service connections
* 1.1.0 Updated data model: Atmosphere and Wind numeric values have been replaced by corresponding Classes (int to Integer and float to Float) in order to support "missing" values in Weather system response.
* 1.0.1 fixed issues on Date parsing and local settings
* 1.0.0 first release