According to the pilot in the tailwheel-equipped airplane, during the landing roll with the tailwheel on the ground, the airplane may have encountered a wind gust. The airplane exited the runway to the left, and the left main landing gear struck a taxiway sign. The airplane sustained substantial damage to the left main landing gear attachment points, the lower fuselage longeron, and the elevator. The pilot reported that the wind at the accident airport about the time of the accident was variable at 4 knots and skies were clear. The METAR nearest the accident site was located 11 miles to the west and reported that the wind about the time of the accident was from 270° at 8 knots, with lightning in the distance to the northwest. The pilot landed to runway 35. Per the National Transportation Safety Board, Pilot Aircraft Accident Report, in the Recommendation section, the pilot asserted that the accident could have been prevented if he had more quickly applied corrective actions including increased right rudder pedal pressure, more differential braking, and increased right aileron input. The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.