As the sun comes out and the temperatures rise, more people are taking their workouts outdoors. But before heading out on a run in the hottest part of the day, make sure your body is prepared for the warmer weather.The No. 1 concern when exercising in the heat is hydration, said Ted Schatz, a personal trainer at Northwest Personal Training in Vancouver.When you exercise in higher temperatures, you’re going to sweat more, Schatz said. To make up for the extra perspiration, you should drink water before, during and after the workout, he said.The standard recommendation is to drink eight 8-ounce glasses of water every day to stay hydrated. That number should go up if you’re losing fluids through sweat, Schatz said.One way to make sure you’re drinking enough water is to weigh yourself before a workout, then again after the workout. The weight difference will tell you how much water you lost, Schatz said.“Then, make sure you replace it,” he said.Your body will also give you clues if it’s starting to get dehydrated, said Dr. Rasjad Lints, a Clark County pediatrician with Kaiser Permanente.