Why does your mouth feel dry?

Your body is dehydrated. Be sure to drink plenty of water, gatorade, juice ect. for the the day before and the the day of your race. Starting to Drink right before the race is to late; start the day before by carrying a water bottle with you and sip from it throughout the day. Try to drink at least 2-3 bottles, the day before in addition to your regular fluid consumption. You'll know when you have had enough to drink when your urine is pale yellow to clear.