Most will associate sun protection with hot summer weather. Applying an SPF 30 or higher when venturing outside when the sun is at its brightest and reapplying when necessary (after excessive sweating or when getting out of the water) is proven to reduce the risk of developing certain types of skin cancer.
The same safety precautions should be implemented year round, even during the winter months as the sun can be as hazardous regardless of the temperature. UV rays are still potent and can penetrate through clouds and can reflect off the snow on the ground, so any areas on the body that are uncovered are venerable. Clothing items such as a scarf are worn to protect from the cold, but it should also be thought of as a clothing item to protect from the sun as the nape of the neck is often overlooked when it comes to sun safety.
Even applying a little amount of sunscreen underneath lighter clothing (such as a scarf) can add extra protection, especially when spending an extended amount of time outside as some fabrics may let UVA/UVB rays to pass through them. Sunglasses or sport goggles for skiing and snowboarding with UV protection can protect the eyes and surrounding areas on sunny days where the snow can be highly reflective.