The pilot was on a visual flight rules (VFR), cross-country flight. He anticipated that there would be an intermittent overcast cloud ceiling and patches of rain along the route, and so he elected to climb above the clouds. The pilot had reached 11,000 ft msl and then began descending to 10,000 ft as night fell. About 1.5 hours into the flight, while still flying at an altitude of 10,000 ft msl, the pilot observed elevated engine cylinder head temperatures. The pilot subsequently contacted air traffic control, declared an emergency, and began to descend through the cloud ceiling that was below him. The airplane exited from the clouds about 5,000 ft agl and the pilot received radar vectors toward a diversion airport that was about 5 miles away. The pilot described that it was very dark with no ground lights visible. As he focused on keeping the engine rpm low to reduce load to lower the cylinder temperatures, he attempted to activate the runway lights at the diversionary airport. After the accident, he realized he had been unable to do this successfully because he had inadvertently remained on the radio frequency with the air traffic controller and not tuned to the appropriate radio frequency to activate the airport’s pilot-controlled lighting. The pilot continued towards the visible airport beacon, still unable to activate the runway lights, and while he maneuvered in an attempt to locate and approach the runway for landing, the airplane struck trees and then the ground. The pilot incurred minor injuries during the accident sequence and the airplane’s fuselage and wings were substantially damaged. The pilot reported that there were no preimpact mechanical malfunctions or failures of the airplane that would have precluded normal operation. He also stated that he believed the elevated cylinder head temperatures were possibly the result of carburetor icing. He did not utilize carburetor heat during the flight. In summary, the pilot’s initial decision to climb above a known area of overcast clouds and precipitation on a VFR flight that would extend into the night resulted in limited options when he encountered an anomalous engine indication. During his subsequent diversion to the alternate airport, the pilot’s distraction due to this issue likely degraded his ability to perform the necessary steps to successfully locate the diversionary runway and perform a precautionary landing. Had the pilot flown the airplane at an altitude that was safely below the cloud ceiling and above the terrain while he attempted to locate the runway, it is likely that the accident would not have occurred.