Elevation and Climate
The Chihuahuan Desert is considered a “high-elevation” desert because so much of the desert lies above 4,000 ft. in elevation. The Rio Grande valley forms the lowest portion of the desert at 1000 ft., while the mountain ranges of Mexico approach 10,000 ft. in elevation.
Winters in the Chihuahuan Desert are typically cool—especially in the northern reaches of the desert where nighttime temperatures drop below freezing over 100 times a year on average. In the summer, daytime high temperatures in the Bolson de Mapimi in Mexico have reached a reported 122º F. The dry early-summer months of May and June are typically the hottest part of the year in the Chihuahuan Desert.
The Chihuahuan Desert is dry because it is bounded by Mexico’s two great mountain ranges: the Sierra Madre Oriental and the Sierra Madre Occidental. As warm, moist air off the oceans rises to move across these mountains, the air is cooled rapidly causing rainfall on the ocean-side of the mountains. The now-hot, dry air flows across the mountains and descends into the basins of the Chihuahuan Desert region.
Unlike the other North American deserts, the Chihuahuan Desert does not have a winter rainy season. Instead, over 90% of the annual rainfall occurs between the months of July and October. This summer monsoon or rainy season is the result of thunderstorms that build in the afternoon and significantly cool the summer days.