Do you still have heat in the heater? If the pump is not turning, you probably won't have flow for normal heat.
Is your coolant good for cold weather? Not sure where you live but it is possible, with poor quality coolant, to freeze the rad in cold weather and have no flow through the radiator. This would cause the engine to overheat.
Lastly, I'd second the votes for headgasket.
Is your coolant good for cold weather? Not sure where you live but it is possible, with poor quality coolant, to freeze the rad in cold weather and have no flow through the radiator. This would cause the engine to overheat.
Lastly, I'd second the votes for headgasket.