As explained in the instruction manual for your Weather Clock, your clock forecasts the weather from its little barometric sensor. The clock has no other senses or inputs to help it choose what weather scene to show. The barometric air pressure sensor checks for rises and falls in pressure and then presents a mechanical weather scene that it thinks is best. So when a Weather Clock displays 'Rain' and there is good weather outside, it will be solely because it has measured a fall in atmospheric pressure. This fall in pressure may be a long term trend (perhaps even taking several days to play out) or a small 'bump' in what has generally been steady and/or high barometric pressure. And this is one of the reasons why solely barometric forecasting has been usurped by more technical meteorology over the years. Your clock's movements can be somewhat unexpected or whimsical at times! If you would like more information or help, please take a look at Help and Advice on Forecasting Accuracy.