Surprisingly, it can be cooler to wear long sleeves and long pants than shorts and a tank top. You want loose-fitting clothing in light colors to reflect the sun and keep it from heating your skin. Go with cotton or linen, which breathe well but also hold moisture (unlike a synthetic, quick-drying fabric). They will keep your sweat close to the body, and as it evaporates, it cools you. Evaporation is a very cheap and very effective way to cool off. Of course it makes the most sense in a dry heat, like in Death Valley, where I live. This might not work as well in South Florida.
—Abby Wines, management assistant at Death Valley National Park and a resident of Death Valley, California, which holds the world record for the highest-recorded air temperature