That's eighth grade, right? Other kids his age are practicing football right now in the same weather. Others have been playing day time baseball. Others are mowing yards for family and grandparents and sometimes for some for coin, too. The young guy does need to hydrate. Give him a water or two if he didn't bring any. And something with some salt in it. And tell him to bring his own forever after. Tell him if he gets dizzy -- not hot, not tired, literally dizzy -- he needs to take a break in the shade. Maybe spray himself with the water. Otherwise, rock on.
Good on him for asking.
If any of us tried to complain about the heat, Dad always said "It's supposed to be hot, it's summer."

That remark has gotten me complaint-free through decades of searing summer days. Unloading steel trucks mid day in sun in the summer for coin when I was in college, for example.