The pilot stated that he was performing touch-and-go landings in light and variable wind at 5 knots. During a landing roll, with the tail wheel on the runway, a puff of wind from the east caused the tail to swing around. The pilot added power in an attempt to regain directional control, when the right wing touched the runway and the airplane impacted a taxiway intersection sign. The airplane's wing spars were structurally damaged and the upper right wing tip was crushed. The pilot stated that there were no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.