The forecast for the flight indicated that there was scattered cloud along the flight planned route, with additional cloud around the ranges. The pilot was advised that the weather conditions would be least favourable close to the DEPARTURE aerodrome, with conditions improving as the flight progressed to the south. Approaching the ranges on the Queensland border, the aircraft was climbed to 9000 feet to overfly what the pilot expected would be a small area of cloud. However, the cloud was found to be more extensive and the pilot descended to regain visual contact with the ground. He then found that he was unable to fly out of a valley because of cloud and rain, and elected to carry out a precautionary landing in a paddock. During the landing roll the nose gear was torn off because of the rough surface conditions. An amended area forecast was issued about five minutes before the aircraft departed Archerfield but this was not relayed to the pilot. The amended forecast indicated broken cumulus cloud between 2500 feet and 10000 feet in addition to broken strato-cumulus between 4000 feet and 9000 feet in the area of the accident.