Apple has acknowledged that there are still problems with the Weather complication on the Apple Watch, even after the release of watchOS 10.0.1. The company has suggested two potential fixes:
Toggle the 24-Hour Time switch in the Clock app settings on your iPhone.
Open the Settings app on your iPhone, tap Privacy & Security > Location Services > Weather, then tap Never, then tap your original setting.
If you have tried both of these fixes and the Weather complication is still not working, you may need to contact Apple Support for further assistance.
Here are some additional tips for troubleshooting the Weather complication on the Apple Watch:
Make sure that your Apple Watch is connected to your iPhone and that both devices have the latest software updates installed.
Restart your Apple Watch and your iPhone.
Try removing the Weather complication from your watch face and then adding it back.
Try changing your watch face to a different one and then back to the one you were using.
If you are using a third-party watch face, try changing to a different one or contacting the developer of the watch face for assistance.
If you are still having trouble with the Weather complication, please contact Apple Support for further assistance.