The pilot reported that during a night visual meteorological condition flight, he was receiving flight following from air traffic control and had to divert around convective weather. The pilot further reported that about 7 nautical miles from his destination airport, the fuel supply was exhausted and the engine lost power. The pilot was able to touchdown on an interstate, but during the landing roll the right wing struck a sign. The right wing sustained substantial damage. During a postaccident interview with the National Transportation Safety Board investigator-in-charge, the pilot reported that he was aware of the weather en-route, but he did not anticipate the length of diversion he received from air traffic control. The pilot reported that he should have departed with full fuel. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.