Not sure where this belongs, but I figured this would be a good start.

I noticed that my windows fog up very easily sometimes when the car is left outside. It seems to happen most when its snowing. I have the heater on (and a/c) which removes it, but if I go out to eat for dinner and come back out to the car, all of the windows are fogged up. Makes no sense how this could happen without anyone being in there.

I clean the windows fairly often with Invisible Glass which removes any film. My guess is maybe the left over snow is creating the moisture.

Any thoughts?