I was unhappy with the new images for kWeather, and I longed for the ones I had used in samurize for windows, so I just took the time to rename the files (based on my own judgment) and replaced the existing ones in
/usr/share/apps/kweather (that's where they are in fedora, anyway).
If this link ever goes down, which it will when I graduate, basically all you gotta do is find a new theme of pngs and rename them. Samurize uses pngs, so any theme you find for that will be useable, just with some alterations, albeit minor.
http://www.susqu.edu/smiley/kweather.tar.gz
enjoy some better weather