Car won't turn over?

problem only affects car in summer. will act like it's vapor-locked. key will turn, starter will click, but no response from the motor. if i kill my car, it will take at least an HOUR before the engine will turn over again if it is left sitting for more than 5 minutes. have checked the starter, starter wires, wiring harness under dash, key ignition, central fuses battery, but have no idea where to even begin to check anything else. i know my car very well, can pretty much fix anything on it if somebody will please just give me an idea of what to even look at. thank you very much, ~*~BEAR