just had a possibly amazing brainwave. all climbers when it rains are cursing and swearing and wondering if it will dry up, so what we need is a table with wind speed and direction, sun and then amount of time to dry out. then in guidebooks or on the internet climbers could look at this table for the a specific crag and know the time it will take to dry out. good idea?
The only other things you'd probably need to know would be local humidity, the amount of moisture in the ground, how wet the rock was to start off with and a perfect local weather forecast.
What I'd find handy is a weather site that showed what the weather has been like for the past few days so you can see whether the crags are likely to be seeping or not, a sort of aftcast.
Route wise, On Peak Rock has a useful Appendix for this sort of thing.