If you want to protect your skin from the aging impacts of UV rays, itβs equally important to apply sunscreen on the darkest winter days as it is on the brightest summer mornings. Thatβs because UVA radiationβthe type that causes dark spots and wrinklesβremains constant throughout the year, no matter the season. Harmful rays from the sun are still present and the UV levels are just as strong as any other season. These rays easily penetrate both clouds and glass, so you can still get exposure on a cloudy day or if youβre sitting indoors near a window.
UVB radiation, on the other hand, does vary in intensity throughout the year. But because UVB rays cause the majority of skin cancer, itβs important to take any possible exposure seriously. While these rays are less strong during the winter months and even weaker if you live on a very northern or very southern latitude, they can still cause sunburns and sun damage year-round in most regions, especially if thereβs snow on the ground.3
Snow can reflect up to 80% of UV rays. That means that youβre actually getting a double dose of exposure: once when the rays hit your skin directly and again when they reflect off of the snow onto your skin. In comparison, sea foam reflects about 25% of UV, and dry beach sand reflects about 15%.5 That means that in the winter season, you might actually be safer from UV rays on the beach than you are on the ski slopes.
In fact, if youβre spending your winter on the slopes, you might also have the high altitude to thank for increased UV exposure. At higher altitudes, the layer of atmosphere between you and the sun is thinner. This means that UV rays have less distance to travel and are stronger when they reach your skin than they are when youβre at sea level.6 This reinforces that wearing sunscreen in winter is still necessary to prevent the effects of sun damage regardless of the season.