Link for fixed and working 1.1.93 Rated 4 out of 5 stars
Here is the link to my revised 1-Click Weather Add-On
Now you can use Silverhawk's steps (which I copied)
To install it:
1) Download the archive from the link above.
2) Remove the existing addon from Firefox and restart Firefox.
3) Click on File->Open and browse to where you downloaded it to.
4) Select the archive and let it install.
I did make the change specified after a bit of research. I updated to Firefox 9 and then followed the above steps to install the add-on and it does work.
If anyone has any issues with it, please let me know right away. Thank you!