Fall and spring are usually warm and pleasant. Summers are hot, although temperatures vary greatly between the desert floor and the Chisos Mountains; May and June are the hottest months. Afternoon and evening rains often cool the desert from July to October. Winters are generally mild, although periods of cold weather (including light snow) are possible. Winter visitors must prepare for a variety of conditions. A wide-brimmed hat, comfortable clothing, and sturdy walking shoes or boots are necessary for anyone planning to hike. Sunscreen is a must. Hikers must always carry plenty of water. One gallon per person per day is recommended.