Remember to drink lots of water! I always aim for 1.5X what I normally drink (so if I drink 8 glasses, I aim for 12) to compensate for what we lose to the heat.
Stay out of the direct sun during the hottest parts of the day. While most think this is 10-2, those are the times that the sun is strongest. Heat accumulates throughout the day, so that the hottest period is often 3-8pm.
Be careful. Stay healthy. And if you can, let someone else pay for the air conditioning. (hit a movie or the mall).