You probably know that you need to apply sunscreen while you’re laying out on the beach. However, dermatologists recommend that you use a sunscreen any time you’re going to be outside for more than 20 minutes, even in the wintertime. You should wear sunscreen even when it’s shady or overcast. The sun’s UV (ultraviolet) rays can begin to cause skin damage in just 15 minutes! This damage can even lead to skin cancer.