You just saved me a good amount of time searching for a solution. Thanks for your post! I changed DNS a couple of days ago and already suspected that for being the culprit of the addon not working properly anymore.
For anyone else something important from the Kodi thread: Disable the Yahoo weather addon’s Auto-update option, then set it from broken to enable. Might require a restart, dunno, you can select it again when choosing which weather addon should be active.