Hello djhl,
Welcome to the Apple Support Communities. We can understand wanting to have the option to check the Weather easily while using your Apple Watch.
To verify, make sure you are following the steps offered here on this page: Check the weather on Apple Watch - Apple Support to ensure all the settings are input correctly to allow you to check the weather on your Apple Watch.
If local weather doesn’t appear on your Apple Watch when you open the Weather app, be sure that Location Services is turned on. Open the Settings app on your Apple Watch, tap Privacy & Security, tap Location Services, then turn on Location Services. On iPhone, go to Settings > Privacy & Security > Location Services, tap Weather, then choose an option.
If the setting are correct and the issue remains, you'll want to follow the guidance offered here on this page: If the Apple Watch Weather complication isn't working - Apple Support. It provides the steps for what to do if weather data on your Apple Watch isn't loading or shows "--".
We hope this information helps you out.
Kind regards!