Firstly, ensure that your Apple Watch is connected to your iPhone and that both devices have a stable internet connection. Sometimes, issues with location services can occur if there's a poor connection or if the devices aren't communicating properly.
Next, try restarting both your Apple Watch and your iPhone. A simple restart can often resolve minor software glitches that may be causing the issue with the Weather complication.
If the problem persists after restarting your devices, you can try resetting the location and privacy settings on your iPhone. To do this, go to Settings > General > Reset > Reset Location & Privacy. Keep in mind that this will reset all location and privacy settings on your iPhone, so you may need to re-enable them for other apps afterward.
If none of the above steps resolve the issue, you may need to contact Official Apple Support for further assistance. They can provide personalized troubleshooting steps or offer additional support to help you resolve the issue with the Weather complication on your Apple Watch.