So I know I do this every year....

But when is it cold enough to turn on the heat? Inquiring minds want to know as it's pretty cold in here. But seriously? I just turned the AC off (again) last week and it feels just WRONG to be turning the heat on less than a week after turning off the AC. Or perhaps I just have hang ups about heating and air conditioning. Fine. CLEARLY I have hang ups about heating and air conditioning. Still, what is YOUR magic number?