After an uneventful 30-minute flight, the pilot set up the tail wheel equipped airplane for a full stop traffic pattern approach and landing. The pilot stated that he touched down normally on the dry asphalt runway heading 050 degrees. Nearing the end of roll out, a "huge" unexpected gust of wind (about 20-25 knots out of the west) lifted the left wing off the ground and pushed the tail to the right, causing the nose of airplane to face to the left. The pilot attempted to correct, but did not have enough rudder authority. The airplane then skidded to the left and went slightly off the left side of the runway. The right wing dug into dirt, resulting in structural damage to the outboard section of the right wing. The pilot stated that he had checked the ATIS information just prior to landing, and the reported wind was 050 degrees at 10 knots with no gusts. Also, he stated that wind "T" indicated that the wind was from about 050 degrees. The pilot noted that he was very surprised when he encountered the crosswind gust on roll out. Shortly after the accident, the pilot demonstrated proficiency in crosswind landings during an FAA check flight.