When temperatures are scorching, a sun hat can provide some much-needed heat relief. But it does more than keep you cool -- a hat can shield you from the sun’s harmful, sunburn-causing UV (ultraviolet) rays. In fact, most dermatologists recommend wearing a hat or sun-protective clothing in addition to slathering on sunscreen. “Many people forget to reapply sunscreen every few hours so wearing a hat is a good backup measure,” says Joshua Zeichner, MD, director of cosmetic and clinical research at Mount Sinai Medical Center in New York City. So which hat fits your fashion sensibilities? Here are the five best styles to help you play it safe in the sun.