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!
Going back to the science of air pressure, if the trending change in barometric pressure is long term, such as a steady drop in pressure from a very high level, it can mean that the clock's forecast represents a longer range prediction. This is often the case when a large anticyclonic area (i.e high pressure area), is over the entire country and is slowly giving way to an approaching low pressure area, bringing with it poorer conditions.
If the trend is short term and just a quick drop in pressure, the clock will revert back to 'Fair' or 'Very Dry' once the 'bump' has passed your area. The drop in pressure may not have brought with it any rain or precipitation, however, the clock still reacted. The clock has no ability to tell if the approaching drop in pressure is going to last or not!
Whatever the case, it can be really helpful to check what the air pressure is doing in your area. If you go to www.darksky.net (a brilliant weather forecasting website!) and input your location, you can do the following:
- Using the 'Time Machine' button lower down the page you can select today or perhaps yesterday's date.
- The page will show several nice charts, one of which will be like the one below showing 'Atmospheric Pressure'.
- From this you can see what your clock has been reacting to and, perhaps, why your clock's forecast is a bit unusual given the weather conditions outside!
If you want to learn even more about how your clock is programmed or correspond with the team about your clock's behaviour, then you can do so via this page.