In reply to natgus:
At the moment the weather is extremely fickle. Yesterday and the day before it poured almost incessantly, but today we had optimal conditions: near-zero temperatures and blue skies. At the moment the forecast is a bit mixed as you can see:
http://www.meteofrance.com/previsions-meteo-france/acheres-la-foret/77760 Saturday looks good and Friday afternoon looks alright, but forecasts are nowhere near reliable. Coldness isn't a problem (quite the contrary, it makes for better friction) but dampness certainly is. Climbing when it's wet in Bleau is everything but fun and potentially dangerous, and anyway shouldn't be attempted at all as sandstone is a very porous and fragile rock (especially so in the southernmost areas like Eléphant and Buthiers, but this holds true for other areas as well), which means by climbing in the wet there's a high chance you'll break holds.
If it rains in the morning but not in the afternoon, head to Rocher fin, 95.2 or Cul de chien, they're usually the quickest-drying areas. Canche aux merciers dries rather quickly too.
My suggestion is to buy the local map (
http://www.amazon.fr/For%C3%AAt-Fontainebleau-trois-pignons-000/dp/27585224... ), which you should be able to find in any library, climbing shop or tourist office, and hike one (or several) of the blue paths. They're absolutely gorgeous. I particularly recommend the one in the Franchard gorges.
