I love windyty! can spend several hours just looking at it, i'm a geographer with a particular interest in climatology, and this is a powerful educational tool i tell you.
I have a couple of questions regarding:
Where is the urban layer coming from, it's pretty neat.
when you go back in time you're viewing old forecast or real data mesaured by the stations?
All in all, congrats, windyty is superb!