In my experience, the biggest problem is the receiver battery. I have flown at temps below -20C/-4F (once), and the fuel was fine. My fingers were not. The receiver battery (nicad) didn't like the temperature at all. After one short flight, the VoltSpy's red lights flashed when I moved the sticks. I admit it, it was stupid to fly, but I couldn't resist. I put the fuselage in the car with the heater on full before flying, and that made it easier to start the engine (ASP FS30AR). It ran fine in the air.