The pilot made a faster than normal approach for a landing on Runway 28 into a strong, gusty, westerly wind. Just prior to the landing flare, the aircraft encountered windshear and the rate of descent increased rapidly. The aircraft touched down very firmly in a slightly nose low attitude and bounced into the air once before landing heavily on the nose wheel. The nose wheel assembly broke allowing the propeller to strike the ground. Except for three hours, the pilot had done all his flying in a Piper PA28-140 (serial number: 28-11018). One week before the accident the pilot had been endorsed on the PA28-235, which has different performance parameters. The pilot did not attempt a go-around because the windshear and rapid rate of descent occurred so close to the ground that he considered the application of engine power would further aggravate the situation. This accident was not the subject of an on-site investigation.