Condensed from CDC.gov
Clothing When possible, long-sleeved shirts and long pants and skirts can provide protection from UV rays. Clothes made from tightly woven fabric offer the best protection.
A wet T-shirt offers much less UV protection than a dry one, and darker colors may offer more protection than lighter colors.
Some clothing certified under international standards comes with information on its ultraviolet protection factor. If wearing this type of clothing isn’t practical, at least try to wear a T-shirt or a beach cover-up. Keep in mind that a typical T-shirt has an SPF rating lower than 15, so use other types of protection as well.
Hat For the most protection, wear a hat with a brim all the way around that shades your face, ears, and the back of your neck.
A tightly woven fabric, such as canvas, works best to protect your skin from UV rays. Avoid straw hats with holes that let sunlight through. A darker hat may offer more UV protection.
If you wear a baseball cap, you should also protect your ears and the back of your neck by wearing clothing that covers those areas, using a broad spectrum sunscreen with at least SPF 15, or by staying in the shade.