On June 30, 2003, at 1145 mountain standard time, a Stinson 108-3, N6216M, ground looped during the landing roll out on runway 14 at St. Johns Industrial Airpark (SJN), St. Johns, Arizona. The owner/pilot was operating the airplane under the provisions of 14 CFR Part 91. The pilot was not injured; the airplane sustained substantial damage. The flight departed Las Vegas Municipal Airport (LSV), Las Vegas, New Mexico, about 11:45 central daylight time. Visual meteorological conditions prevailed and no flight plan had been filed. The pilot reported the purpose of landing at St. Johns was to refuel. He checked the automated surface observation system (ASOS) and noted it was an hour old. He then overflew the airport and checked the windsock. The windsock was indicating wind conditions 180 degrees different than the ASOS. The pilot then called on the Unicom and verified that the winds were blowing opposite the direction as indicated on the ASOS. The Unicom operator, who is also the airport manager, confirmed the pilot's observation, and the pilot landed the airplane. During the landing roll out, the wind shifted from a right quartering headwind to a right quartering tailwind that blew the airplane to the right. It ground looped, impacted a ditch, and bent the left wing approximately 3 feet inboard of the wing tip. The pilot did not report any mechanical malfunctions prior to the accident. The METAR reports for the St. Johns airport were reviewed. At 1154, the winds were from 260 degrees at 14 knots. For the 1254 observation, the winds were from 300 degrees at 7 knots, gusting to 15; the winds during the hour were noted to be variable from 230 to 030 degrees.