Forecastfox is a GREAT add-in. I get a week's worth of weather info at a glance - always there, always updated.
However, I have no good things to say about Firefox development which seems to want to trash Forecastfox every couple of updates. I stopped updating Firefox for a while because it kept killing off Forecastfox. Now, it's done it again.
Why would Firefox deliberately keep kicking its most popular add-ins into the dumpster? I got onboard with Firefox at Version 1.5, but I'm looking for a better alternative now.