Some users report Weather complications showing no data when running watchOS 10. Issue is still reproducible with watchOS 10.0.1 and 10.0.2 (which was released for Series 9 and Ultra 2). Apple suggested couple of workarounds until the issue is resolved with software update.
Third party apps might also experience issues with updating complications.
- Apple Watch Users Report Weather Complication Issues in watchOS 10
- watchOS 10.0.2 Fixes Weather Complication Bug on Apple Watch Series 9 and Ultra 2 [Update: No]
- Apple Suggests Potential Fixes for Weather Complication Bug on Apple Watch
- Apple Releases watchOS 10.0.2 for Apple Watch Ultra 2 and Series 9