The pilot of the float-equipped airplane reported that he overflew the river where he planned to land about 1,000 ft above the water. He observed "negligible surface clues" indicating wind direction and recalled that a nearby "ATIS" reported the wind as "light" and from the southwest, so he decided to land to the south. He added that, following a normal landing touchdown, as the airplane was slowing, a "sudden moderate to severe gust of wind came from the right to left." He added that he "inputted right stick to counter" the wind gust and applied power to "go-around," but the airplane nosed over forward and to the left. The fuselage, empennage, and both wings sustained substantial damage. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. An automated weather observation station 14 nautical miles (nm) southwest from the accident site reported, about the time of the accident, wind from 340° at 3 knots. The departure airport about 30 nm northeast reported, about the time the pilot departed, wind from 300° at 4 knots. The pilot reported that the wind was from the southwest, gusting to 10 to 15 knots. He added that the landing direction was to the south.