In addition to packing the right gear, don t forget to bring along water. If you are planning on a day of long approaches and multiple pitches, double that amount. Drink fluids before you get thirsty. A good way to monitor your level of hydration is to watch your urine. If it is clear, you have nothing to fear.
Yellow urine is a sign of dehydration.
Even worse is when you are drinking and not urinating, because your body is utilizing all of the liquid you are consuming. In both cases, drink more. Another sign of dehydration is a headache, accompanied by a sick feeling and lack of thirst. In this case, force yourself to drink fluids. Humidity is your enemy.