With the weather we're having right now you should leave your vehicle plugged in all night if it is parked outside. Otherwise it won't start in the morning. If it's inside, even if the building is not heated, you likely wouldn't have to plug it in at all if your battery is strong. If mine was outside and not plugged in, I'd want to start it up and run it a while every 4 hours or so in this weather.
My wife and I are leaving for Arizona in a few days and it's looking better all the time.
