The following advice was passed on to a new Bat Girl model attending an upcoming car show in muggy Florida.
"Wear underarm pads, if possible; wear a sweat band under the cowl; drink enough water, but not so much you have to run to the bathroom constantly; and turn to the breeze whenever possible. "
(from the 1966 Batman Message Board.)
Uncanny thinking from an apparently seasoned Crusader.
They tell me that Superhero cowls, the head piece, have no air circulation and get uncomfortably warm very quickly.
And I am assuming the tights don't breath well, either.