On May 9, 1999, about 0700 hours mountain standard time, an Aerostar International, Inc., S-60A balloon, N3592Z, operated by the Aerozona Balloon Company, Sedona, Arizona, made a high wind landing near Clarkdale, Arizona. The balloon was not damaged. The commercial pilot and three passengers were not injured; the fourth passenger was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 CFR Part 91 aerial sightseeing passenger flight. The planned local area revenue flight commenced from Black Canyon, Arizona, about 0605. The pilot reported that he performed a high wind landing, and all of the passengers were wearing safety helmets. The pilot stated that he ripped open the envelope's top after touchdown. The basket was dragged about 10 feet before coming to rest in terrain, which had vegetation over 1/2 of its surface. While being dragged, a branch/limb from a small tree penetrated the basket through the passenger's step hole. The branch contacted a passenger's leg, which resulted in a serious injury. The pilot indicated that the local wind was from 140 degrees, at 8 knots. The visibility was 50 miles.