Good point, I hadn't thought of that. It's basically natural for me to keep drinking water and making sure I eat well when it's this hot.

I tell people that it's possibly more important to drink water before you go outside -- even better, the night before. I think (therefore, I can't verify ) that the body needs some time to absorb water into its systems, so getting well-hydrated beforehand gives yourself a chance to turn that water into sweat. After all, it's got to move from your digestive system to your skin -- nobody (at least, nobody I know of) uses urine to cool off.

And keep eating, too. No need to overeat, but over-hydrating can be a real problem as well. I can't say that lots of sweating would prevent it, but I've read about enough instances of people dying that I just stay with reasonable amounts of water. Poke around for overhydration hyponatremia for more info.