A few years back I saw a study that reported that cold viruses survived longer outside the human body in cool temperatures than in warm (not below freezing, but

A few years back I saw a study that reported that cold viruses survived longer outside the human body in cool temperatures than in warm (not below freezing, but the equivalent of refrigerating them.) That makes sense, and since you won't get a cold unless you pick up a viable cold virus, this would imply that the chance of getting a cold would be higher in cooler weather, because there are more cold viruses on the surfaces around you that haven't yet been denatured by heat. I don't know if this hypothesis has been explicitly tested, but it seems to me as though it could explain why people get more colds in winter than in summer but are not usually made sick by playing in the snow or taking a plunge in frigid water. The cold doesn't do anything to the people, it just preserves external viruses longer making the environment "dirtier".