Healthy people with normal immune systems are highly susceptible to cold virus infection once the virus enters the nose. Why people sometimes become infected but do not develop cold symptoms is a mystery. Central heating dries the mucus membranes of the nose and makes a person more susceptible to catching a cold. The nasal mucus membrane is very resistant to the effects of low humidity.
Low humidity makes the nose feel dry but the mucus membrane still continues to work normally.
The cold season in the United States typically begins in late August and early September at a time when temperatures are still moderate and central heating is not being used. Becoming cold or chilled leads to catching a cold. As discussed above, almost everybody becomes infected whether they are chilled or not, if cold virus is dropped into the nose. One study has looked at this question. It was found that colds were no more frequent or severe in volunteers who were chilled than those who were not.