My house has basement and one floor. When outside is 7 to 10 degrees warmer than the day before, bedrooms, living room always get colder. where did the cold air come from? I am assuming cold comes from basement. I know cold air always is at bottom...heavier than warm air near the ceiling...lighter. When outside becomes warmer, cold air near the floor starts to rise and push warm air even higher. Is that reasonable that it's how I feel colder when it's warmer outside? It must have hidden somewhere unless warm air at the top becomes cold due to air molecules become less vibrant resulting colder. But it should not be cuz I have two windows per room.big enough for sunlight to come through. I think it has to do with ventilation.