According to the student pilot, during his fifth solo flight, he struggled to keep the nose straight during the landing on runway 31. He reported that during the touchdown the airplane porpoised, the nose gear collapsed, and the airplane came to rest on the runway. According to his certificated flight instructor (CFI), the student pilot was endorsed to fly the airplane in a maximum wind velocity of 8 knots. The meteorological aerodrome report (METAR) indicated that the wind at the time of the accident was 310 degrees true at 15 knots, gusting to 22 knots. According to METAR data the wind velocity exceeded the pilot's endorsed limitation at 0747 Pacific daylight time (PDT), and did not subside during the remainder of that day. The student pilot's solo flight commenced at 1259 PDT. The airplane sustained substantial damage to the firewall. The pilot reported that there were no mechanical failures or anomalies with the airplane prior to or during the flight that would have prevented normal flight operation.