The pilot reported that during the landing flare a gust of wind "picked up" the right wing and "spun" the airplane to the left. The airplane veered off the left side of the runway and came to rest in a ditch. The airplane sustained substantial damage to the forward portion of the fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions of the airplane that would have precluded normal operation. An automated weather observation system located about 13 nautical miles from the accident site reported that about the time of the accident, a right 70° crosswind wind at 8 knots prevailed.