Like many of you, I saw Yahoo Weather get marked as broken and cease functioning recently. Since many of us will be using 18.9 for a while and the new weather addon will not be backported to Leia, a kind user on the Kodi forums posted a quick fix.
You just need to replace the ‘default.py’ file in ~/.kodi/osmc/addons/weather.yahoo with this one, disable auto-update, and re-enable the addon. It’ll be working again after a reload (switching the default weather addon back and forth should suffice).
Source: Yahoo! Weather
UPDATE: Was much easier than I expected to turn this into an installable zip file. I upped the version to 18.104.22.168, removed the “broken” tag, and put the author as “skirge dba zambu” to give full credit to the original author. Use whichever method you prefer.
Installable zip file: Dropbox - weather.yahoo-22.214.171.124.zip - Simplify your life