The watch complication is pretty much useless as it is now. It says “Windy”. That’s it — doesn’t add any information to the watch face.
I’m currently using My Radar in that complication spot. It can be configured to display temp or any of a number of pieces of info. Tap on the complication and it brings up weather radar.
I really like the radar display in Windy, and I love that it can show data from my personal weather station. Please consider giving the watch complication a little more thought.