Weather only knows about airports
As fas as I can tall, Weather uses libgweather, and libgweather only knows how to pull weather data for airports[1] (if that airport has an ICAO code, and if that airport publishes all the required weather data). This results in wildly inaccurate weather data for many, many places in the world, and a lot of "I can't get weather data for place X" bug reports.
It would be nice if GNOME Weather could look at more places than air ports.