How are some animals apparently able to sense outdoor temperatures from within a heated house?

I have many cats & dogs. All go in & out. However, come fall & winter I have several who have no interest in poking their nose beyond the door in cold weather. The dogs go out regardless but on cold days none of them seem to be in as big a hurry to pee. Now snow, rain, wind are visible & audible I get that but how are they able to gauge the air temp when they are snuggled up indoors next to the wood stove?