Understanding the Causes of Dry Skin in Winter The cold air outside and heated air inside create a perfect storm for dry skin. When temperatures drop, the air holds less moisture, which means your skin loses water faster. Indoor heating systems also reduce humidity, further drying out your skin. In Minnesota and Wisconsin, winter humidity levels can drop below 20%, compared to 30-50% in warmer months. This low humidity causes your skin’s natural oils to evaporate, leaving it