The pilot made one local flight and a short time later departed on another with a club student pilot as passenger. His intention was to go to the training area but soon after departing the circuit he became concerned by rain showers close to the aerodrome and decided to return. As on DEPARTURE, runway 18 was used and the surface wind was light and variable. Rain was encountered and on final approach it became heavy, significantly reducing forward visibility. The pilot's landing technique on the aircraft type was to flare fairly high on the approach and adjust power for the final descent. The aircraft suddenly dropped from about 40-50 feet above the runway, contacting the surface very heavily. Aircraft damage was sustained as a result of the heavy landing. It is considered probable that the heavy landing was the result of the aircraft stalling on final approach.