It's been reported that WeatherCat for the Apple Watch will sometimes display a blank screen even though WeatherCat on the iPhone is working properly. To correct this condition, kill and restart WeatherCat on the iPhone. Don't restart the iPhone, just WeatherCat. To kill and restart WeatherCat/iPhone, go to the iPhone Home screen, double-click the Home button, and swipe the WeatherCat screen image upward. Return to the Home screen and tap WeatherCat to restart it.