Give your scalp air and try a straw hat. Straw is perfect for warmer temperatures because it's lightweight and naturally vented to keep your dome comfy as the mercury rises. J.J. Hat Center does some dope modern versions of straw trilbies with a bill. It's the like summer's answer to the fitted cap.
Half Sleeve Shirt
Buy It Now at Mark McNairy, $125
C.C. Milan Stingy
Buy It Now at J.J. Hat Center, $130