The private pilot was landing on a 1,300 foot long dirt landing strip at his rural residence. He estimated the quartering right headwind as 17 miles per hour with gusts to 23 miles per hour during his approach to land. The pilot encountered an “extreme gust of wind” as the airplane touched down. The airplane drifted off of the left side of the runway and into freshly plowed ground. The nose gear impacted a furrow and the airplane nosed over on its back. There was substantial damage to both wings, the vertical fin and rudder, engine mounts, nose gear, and firewall. Both occupants exited the airplane unassisted and reported that they were not injured.