A character can accurately judge how difficult a climb will be if he/she makes a dice roll using his/her PE + Climbing (including Judging difficulty specialism). The difficulty value is the climb difficulty (used for climbing safely dice rolls, see Climbing safely). If the character fails, he/she will know that the climb looks more difficult than the dice roll result he/she achieved but not how much more difficult.
For example, Urlik is a good climber with a Climbing skill of 3 but no points of specialism in Judging difficulty. He has a PE score of +0. His basic value for judging the difficulty of a climb is 3+0=3. When judging how difficult it will be to climb a cliff, he chooses to risk two dice giving him 2D-3. He rolls a six and a five, giving a dice roll result of 8. The actual difficulty of the climb is 7, so the referee tells Urlik's player this.