If It's desert, just wear loose fitting light garments and let the sweat cool you.
I worked in hotter temps (driving sheeting building seawalls) in 99% relative humidity, and the only way to cool off was to go into the water. Sweat didn't evaporate well there. But in the desert, drink a lot of water, have some salt (ekectrolyte tabs are best, because they have some potassium), and sweat, preferably where there is shade and a breeze.