The app now supports watchOS 4 and can potentially have a complication, however in testing the complications have a very small CPU and network budget, so it can only update a few times per hour, then it gets stuck on the last update. This makes it show the wrong prediction for a while. I’m looking into ways around it to reduce the CPU and network, but it is a fundamental issue with the way complications work in watchOS.Ian commented
I bought the App for an Apple Watch 3 expecting it to show radar for my area as advertised. It only shows one data screen which is really disappointing for a paid App.