For many people, chapped lips are a fact of life, especially when the weather changes. Extreme heat or cold coupled with dry air leach moisture from the skin, causing dryness and flaking — particularly on the lips, where skin is thin. “In the winter there’s way less humidity in the air and so the cold air pulls moisture from the skin,” says Kiran Mian, D.O, a board-certified dermatologist at Hudson Dermatology and Laser Surgery in New York City.