Good point. I wouldn't consider it adware since it does provide a useful service I don't mind advertisers subsidizing. What I do consider adware are pure ads that are forcibly foisted upon me without my knowledge and my consent. As far as true adware is concerned, my attitude has always been that if advertisers want to turn my computer into a 24 hour bulletin board for crummy ads, they ought pay me to display them.
Absolutely. I feel the same way about those stickers car dealers put on cars, and I've told them so.
I can be pretty damned curmudgeonly/crotchety about these things, but it's the principle.
The only drawbacks I can see for the firefox weather extensions are (a) they might decide to go to an ad basis since Firefox has exploded in popularity and (b) the weather is not visible if the browser is not running.
As for those drawbacks, if ads appear I'll deal with it then, and since my browser is constantly active (with FR, of course), the weather forecast is also always there.