UVB rays, the main cause of sunburns, are the strongest in the summer. However, UVB rays can burn and damage your skin year-round, especially at high altitudes and on reflective surfaces such as snow and ice. Snow reflects 80 percent of the sun’s UV light, further increasing risk of skin cancer and premature aging. The Skin Care Foundation urges you to cover up, wear UV-blocking glasses and apply a broad-spectrum sunscreen with an SPF of 15 or higher daily to all exposed skin.