Notes

Regardless of the latitude, longitude, and elevation, a harsh and extreme temperature regime exists in the North American Desert, with a high frequency of cloudless days and intense solar radiation, infrequent and intense storms, winds carrying dust and sand, low relative humidity, and rapid evaporation or sublimation of snow. Regionally specific climatic zones exist, ranging from temperate in the Great Basin and Painted Desert to subtropical in the western Sonoran and northern Chihuahuan sections to tropical in the Sonoran gulf coast. Average annual temperatures range from approximately 49° F (9° C) in the northern deserts (Black Rock) to 73° F (23° C) in the Sonoran Desert and 77° F (25° C) at the bottom of Death Valley. Average annual rainfall varies from 6 to 12 inches (150 to 300 millimetres) in the Great Basin Desert, 2 to 6 inches in the Mojave Desert (a low of 2 inches in Death Valley), 10 to 11 inches in the Red and Painted deserts, 8 to 18 inches in the Sonoran Desert, and 12 to 14 inches in parts of the Chihuahuan Desert. Precipitation may be seasonal and characteristically is erratic, scattered, or intense. Snowfall of 12 to 24 inches occurs in most of the northern deserts, decreasing to only a trace in the Sonoran Desert. Winds are directional, with speeds averaging seven to nine miles per hour. Average relative humidities are generally less than 50 percent (20 percent for Death Valley), but 10 percent or less is not uncommon. The growing season varies from 90 to 140 days in the northern deserts to more than 300 days along the Sonoran gulf coast and in the Baja Peninsula.