In His Absence... Rated 5 out of 5 stars
As you may have noticed, Silverhawk hasn't been around in over a year, the link he posted is broken, and the fix he wrote needs an update. I don't know why he hasn't come around, but in his absence if you need to download the file he posted just do a Google search for it (1-clickweather-220.127.116.11-fx.xpi) and you can find it on several websites or forums. As far as it not working in the latest versions of Firefox, I can only say it should work in versions posted prior to his last appearance on this page, which was May 31, 2012. If the post by beachdreamwitch on October 24, 2012 is any indication, it's possible that FF 15.0 is the last safe version for this add-on. Kudos to Silverhawk for updating this great add-on that the new owners of The Weather Channel choose to ignore.
Also, if you're interested there is a really well done interactive weather map available on intellicast.com (another company owned by the company that owns TWC) that goes well with the functionality of this add-on. You can't download it or anything unless you pay big bucks to license the use of it on a website, but you can bookmark it and or use it as a home page. I have found it pretty useful for watching the local radar and satellite displays.