After having inspected a property, the pilot and his passengers returned to the aircraft to prepare for DEPARTURE. A storm was approaching the strip from the north and a 10 to 15 knot crosswind prevailed at the strip. A take-off into the east was commenced, the aircraft became airborne and as it crossed the upwind end of the strip, it was affected by a sudden gust of wind. The aircraft yawed to the right, lost altitude and struck the ground, before coming to rest in a ploughed paddock. At the time of the attempted take-off the location of the approaching storm was conducive to the presence of strong downdraughts or possibly microbursts in the vicinity of the strip. The pilot elected to commence the take-off because he was concerned that heavy rain at the strip would have rendered it unserviceable.