I have that also. Did you open it's settings and set it up? Do you have;

https://addons.mozilla.org/en-US/firefox/addon/forecastfox-fix-version/ Forecastfox (fix version) Get international weather forecasts from AccuWeather.com and display them in any toolbar or statusbar with this highly customizable and unobtrusive extension.

If not, remove what you have and get this one.

Thanks for your help. That is the version I added to the Toolbar. It acts like it is working (and should with the default settings). Then I close down Firefox. Later, when I start Firefox again.....no forecastfox.

Right now, as far as I know, I have the same versions of Firefox, the Addon bar, and Forecastfox on 2 computers. One works and one doesn't. I have a feeling that there must be some small thing I'm not doing right, Or as we say down south, I ain't holdin my mouth rite.

http://forums.mozillazine.org/viewtopic.php?f=48&t=2913287 Support site

Thanks again Fred. My solution was to put Weather.com on my bookmark toolbar. I liked the "hover over the green dot" radar though.

Well, whatever. That was very good work. Well Done. Please flag your last post as Solved Problem so others will know.