The Chihuahuan Desert is a perfect example of the old saying that "bigger is not necessarily always better." While this desert area is the biggest of the major desert areas in North America, life here is hard. Yet as hard as it is to survive in this arid locale, many species not only survive; they thrive. The Chihuahuan Desert is the largest of North America's four desert regions. At 175,000 square miles (although some sources put this figure closer to 200,000 square miles), the Chihuahuan Desert is larger than the state of California. This translates to approximately thirty-six percent of the total desert area of the continent. It occupies a small portion of southeastern Arizona, parts of southern and southeastern New Mexico, and extreme west Texas. The majority of the Chihuahuan is found in north central Mexico.
CLIMATE
The climate of the Chihuahuan Desert is what one would expect of a hot desert. Rainfall averages 8.65 inches to twelve inches at the highest elevations. Daytime temperatures range from 50°- 65° F in the winter to over 100° during the summer. Nighttime temperatures drop below the freezing point at least one hundred times per year. Snow is not uncommon at the higher elevations of the Chihuahuan Desert during the winter months.
Scientists describe the Chihuahuan Desert as a rain shadow desert. This is due to the fact that the area in Mexico is located between two major mountain ranges. The Sierra Madre Occidentals lie to the west, preventing moisture from the Pacific Ocean from reaching the area; and the Sierra Orientals on the east have the same effect with moisture from the Gulf of Mexico. The rain shadow effect produced by these two mountain ranges led to the development of this area as a desert. The area of the Chihuahuan Desert that lies within the United States also has its share of mountain ranges. In Texas, one finds the Franklin Mountains. The San Andres and Dona Anas ranges are found in New Mexico.
ELEVATION
Minimum elevation in the Chihuahuan Desert is 1,000 feet above sea level. However, the majority of the area lies at elevations between 3,500 and 5,000 feet.
This desert area shares geographic features with the other desert areas of North America including alluvial plains, bajadas, and some scattered mountains. Soils in some areas of the Chihuahuan Desert provide evidence of the volcanism that occurred in the area during the Eocene and Miocene eras (58 to 113 million years ago).
WATER IN THE DESERT
Although the Chihuahuan Desert is arid during the majority of the year, it has one period of high precipitation during the summer. Rainfall during the months of June and July is so heavy that the storms that bring it are called monsoons. Ephemeral streams, lakes, arroyos, and large puddles fill during this time and temporarily support various forms of life. However, as the water evaporates and the climate returns to its more humid and arid state, the species that have found moisture there move on to a more constant source of water; or they return to a state of estivation and await the water's return.
One should not think that this area is without water except during the rainy season. This desert has several water features that are present year round. Five major rivers are found either partially or totally within the Chihuahuan Desert. These rivers include two thirds of the Pecos River, one half of the Rio Grande River, the majority of the Gila River, and the headwaters of the San Francisco River
