According to the pilot, immediately after lift-off, the prevailing wind shifted from a headwind to a tailwind and he was unable to maintain aircraft heading/runway centerline. The airplane was blown toward the runway edge and settled onto the dirt beside the runway. During the roll-out, the airplane struck a taxiway location/runway holding position sign midway between the passenger compartment and the empennage resulting in the empennage being bent approximately 70 degrees to the right. Weather reported at the time of the accident was; wind variable at 5 knots, 10 miles visibility, clear skies, temperature 18, dew point minus 4, altimeter setting 30.00 inches. The pilot reported no mechanical anomalies with the airplane prior to the accident. An examination of the airplane revealed no mechanical anomalies.