Similar to the seasons, skin goes through its own fluctuations. Combine nature’s weather cycle with air conditioning and forced-air heating, and you have skin that’s constantly under assault. Cold winds and low temperatures can dry out skin, depriving it of balanced levels of oils, contributing to dryness, sensitivity and premature aging. Prolonged exposure to the sun causes water to evaporate from skin, which is why skin that has recently been burned or tanned requires more moisturization than unexposed areas. Forced-air heating also dries out skin: warm, dry air acts like a sponge, soaking up moisture from everything it touches.