I've been looking for some weather data sources that don't require web scraping.  Here's what I have.

• http://developer.yahoo.com/
• http://www.weather.gov/ 
• http://www.weatherbug.com/api/default.asp

It's good to note that there are a lot of really great sources of data at Yahoo's developer site.  This includes traffic data, a dcent map api, search functionality and more.  Google maps has a map api as well.