Stop in for a cup of coffee

Yes, when you wake up and can't see 20 feet in front of you, it's from cold air hitting warm areas. Foggy ! What is it you don't understand?
I was thinking you meant Fog Days like in Snow days for schools where they close school for Fog. Was gonna say that was nutty. My daughter's school canceled... over 3 inches of snow, thats now melting because its already 35.