Humidifiers help. The issue of mold is particular concern to me so I have to be careful when it comes to using a humidifier. However, I have found that if I drink enough non-caffeinated beverages throughout the day it takes care of the majority of the problem. Cold weather has a sneeky way of sucking the liquid right out of your body. Look at what happens in the fridge it something is not properly sealed. The same thing happens to the body. Having lived in upstate New York, northern Maine, Alaska, Tucson, The Republic of Panama, and Oklahoma (to name a few places) I have found that proper body hydration is the key.