DO NOT CLIMB ON WET SANDSTONE

Rule of Thumb: If the 24hour sumline for precipitation is above 0, rather refrain from climbing and spend your day differently. Take a nice hike or visit Fontainebleau or one of the surrounding villages
A guide on what to do in or around the forest is planned

The Fontainebleau-Sandstone is very porous and remains wet inside even if the outside appears to be dry. The stone becomes very fragile when wet/damp. Climbing on wet rock will make the holds more fragile, so they will break (often they can break after they have dried if they were climbed on when wet). It happens constantly. Therefore, please let the inside dry a bit longer and don't try to dry them with fans/leafblowers or tissues. It will only dry the surface, but won't reach the inside

Some useful resources:

How to tell if a hold is wet

The beaufort wind scale

Precipitation Levels (Please don't think, that light rain means, it will be instantly dry again.

Information created from data from Météo-France