Then you go the the DTI (www.dti.gov.uk) website and there is a section there for weather conditions (I didremember exactly where but if I can find it, I know you can!), type in the OS number, and it gives you all sorts - windspeed, sunshine, rainfall etc etc.
All very nifty if you can get it to work. Which I couldn't. But then I'm rubbish at all this computer stuff anyway.
