Michael Whitehurst, professor of exercise science and health promotion at Florida Atlantic University, explains how to stay properly hydrated as the temperature soars.

[ 1 ] Beat the clock: Exercising in hot, humid conditions can dehydrate a person in 30 to 60 minutes, depending on the activity and the individual. “If you’re an athlete, you’re going to sweat more profusely—and the timeline for dehydration [will] be shorter,” Whitehurst says.

[ 2 ] Anticipation: Thirst is the first clue that you’re dehydrated—but that’s typically too late, Whitehurst says. Hydrate before you feel thirst. Another way to tell that you need more water is if your urine looks darker than usual. The darker your urine, the more dehydrated you are.

[ 3 ] The Rule of Salt: A salty snack can help you rehydrate during a long or highly intense workout. Emphasis on long or intense. Whitehurst says you have to lose a substantial amount of body weight—probably 2 to 5 percent—during a workout to worry about salt replacement. “If you’re exercising moderately, under an hour, salt replacement outside the regular dietary intake would not be necessary,” he says.

[ 4 ] Drink Responsibly: It’s possible to over-drink during a workout. Too much water can cause symptoms from nausea to, believe it or not, coma. The International Marathon Medical Directors Association recommends that athletes drink no more than 31 ounces of water an hour when exercising. Whitehurst suggests rehydrating about every 20 minutes.

[ 5 ] Feel the Heat: Not accustomed to exercising under the sweltering Florida sun? Try acclimating slowly over the course of two weeks; get your body used to sweating, then cooling down. Practice hydrating, as well, so you can understand what your body needs and when, Whitehurst says.