exercise early in the morning
drink plenty of fluids before, during, and after your workout
exercise late in the evening, when the sun is going down and there's a breeze
Drink fluids with salt, such as commercially availble electrolyte beverages
exercise in a cool environment, such as a gym with A/C
Regardless to how much you exercise or go out in the sun, be sure to drink plenty of fluids throughout the entire day. In this heat, you're most likely sweating all day and evening, without even realizing it, therefore should replenish your body with the fluids it needs!