A proper hand crack in Font! Tape gloves and solid jamming technique required. Sit start at the right end of the crack and traverse left to where the crack turns upwards. From here climb the arete to the top.
Fun jamming to a little change of style in Font. Be aware of the flake inside the crack that seems a little fragile, don't crimp behind it, commit to that jam :-) The move at the corner benefits from a large undercut low on the left.
Rain sucks, but broken holds suck even more. Remember, never climb on wet rock in Fontainebleau.
The sandstone becomes brittle, and pulling on it will ruin classic problems. Drying it doesn't help, because it's still wet and weak inside.
All you can do is wait for better conditions.