There are major changes again to the Metar data source at aviationweather.gov. Not only URL changes, but changes to the parameters to the API, some have been dropped or become part of the URL. Data API
The weather stopped working for me this morning, so I have removed my location so it no longer tries to call the API.
I think it will be a long time before the clock applet will show the weather once more if ever.
We can hope for Ubuntu Mate 26.04