The student pilot and his certified flight instructor performed three takeoff and landings at the accident airport in preparation for the student pilot's second solo flight. During these three takeoff and landings, the winds were from the northwest at 8 to 11 knots with no wind gusts. After approximately 0.7 hours of flight time, the certified flight instructor exited the airplane, and the student pilot taxied to runway 28L for takeoff. About the time of departure, the winds began to gust to 17 knots. The student pilot stated that during the landing flare on runway 28L, he experienced a "downwash" and the airplane "ballooned and turned to the right." The student pilot added "some power" and applied rudder, but the nose wheel hit the runway and the airplane veered off the runway. The certified flight instructor placed a maximum wind limitation of 15 knots on the student pilot's initial solo endorsement.