Umbrellas offer protection from UV rays, but that level of protection depends on the umbrella. While all umbrellas protect you some, you can still get sun at your table. The average patio umbrella blocks about ⅔ of UV rays or up to 85 percent. Some umbrellas have an added layer of UV protection. How much sun blocking you get depends on the size of your umbrella and even the color of your umbrella. In other words: don’t use an umbrella in place of sun protection! Without sunscreen, you can still get a burn within 30 minutes to an hour.