Since you'll be drinking a lot, pop will cause you to feel bloated. As well, some pop contains caffeine which dehydrates and leads to hyperactivity - just what you want to avoid on a hot day. Alcohol is to be avoided too. It does not quench thirst, tends to increase the sensation of body heat, and also causes dehydration. Wear a hat.
Heat exhaustion is a possibility, so a light- coloured hat is recommended to shade the head.
Rest from walking often. Seek shade or an air-conditioned theater when overheated. Drink water with a mild amount of salt. Carry some travel moist towelettes with you. They come in foil packages.