For firefighters, fighting Arizona heat starts long before the emergency call comes inWhen temperatures climb into triple digits, most people take refuge indoors. How does extreme heat change the way firefighters approach a shift? What does extreme heat do to a firefighter’s body? Do your most strenuous activities in the early morning or evening, and hydrate, hydrate, hydrate. By the time you stop sweating, you’re way, way, way behind the eight ball.