As a board certified dermatologist, I perform skin cancer screening all year round, and my counseling on sun protection and avoidance measures to reduce the risk of skin cancer doesn't change, not even in the winter. No, I'm not out of touch with the seasons. I have seen sunburns in the dead of winter, and the cold temperature doesn't mean there isn't any UV radiation. I have patients who enjoy winter sports such as skiing and snowboarding, and I have come across the occasional "reverse raccoon" tan or burn pattern, where their lower face is tanned or burned but they have sparing of the eyes because they were wearing goggles. Those goggles manufacturers know what is going on with sun exposure in the winter time as quality goggles have a protective anti-UV coating or are made of materials with inherent UV blocking properties. To make matters worse, when it snows, everyone gets exposed to the mirroring effect from the UV radiation, not just directly from the sun, but then they get a second hit (or third or fourth) from the UV rays reflected off snow. In the worst of cases, people who have a history of cold sores will develop outbreaks because the UV rays induce the herpes virus to come out from the lips. So protect your whole face, wear a sunscreen even in the winter, and wear lip balm with SPF30 sunscreen or higher rating. If you are physically active or participating in a winter sport, use a sports sunscreen like Banana Boat Sunscreen Sport Performance Faces Broad Spectrum Zinc Sun Care SPF50 Sunscreen which is waterproof and doesn't sting if it gets in your eyes.
If you are worried about a new or changing growth, even in the winter, come in for a skin check (and get some free sunscreen samples).