Please verify that you installed the companion app of the watch face, as suggested in the watch face settings on your watch.
You also need to enable data and gps on your mobile, and that both are at bluetooth range.
These are the only requirement to get weather.
You can check your mobile settings, maybe do you have some “economy” mode for battery saving, or something like that, which prevent service to run, or to access gps.
Also verify in the settings of your mobile in the “applications” category, that you did accept all the permissions for the app.
Weather results will then depends on the data sent by openweathermap.com or yr.no (it depends on your choice in the watch face settings).
After choosing a provider, hit the “update now” button to test it.