The old adage "if you don't like the weather, just wait a minute," often holds true in Big Bend National Park. While Big Bend generally has blue skies and warm days, the weather can change quickly and dramatically. You should be prepared for just about ANY type of weather at any time of the year.
Through the Year
Relative humidity is usually low. The rainy season extends from mid-June to October with locally heavy thunderstorms and some flash flooding. However, the water recedes rapidly and the rainy season can be a delightful time to visit the desert. 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.
Elevation is Everything
Air temperature changes by five degrees for every 1,000 feet of elevation you gain or lose; temperatures in the high Chisos Mountains can be 20+ degrees cooler than temperatures along the Rio Grande. Prepare for this kind of variation during your trip.
Dress for the Weather
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.