Met.no LocationforecastLTS API states that this version of the webservice is deprecated, and the plugin needs to be adapted to use a newer version, or it will stop working within a few months. Please file a bug on https://bugzilla.xfce.org if no one else has done so yet.
This bug is most likely already fixed in the latest releases: https://git.xfce.org/panel-plugins/xfce4-weather-plugin/commit/?id=abd77251273d0cfaac29c883217dcfdb5b257830 To answer your question: yes, the plugin was last released 6 weeks ago. *** This bug has been marked as a duplicate of bug 16268 ***