There is moisture in desert air.
“The humidity of the Mojave Desert changes throughout the day and night and from season to season. Average daytime relative humidity ranges from 10 percent to 30 percent. Nighttime humidity can be as high as 50 percent. Humidity is higher before and after the Mojave’s infrequent rainfalls; it tends to rise at night and during cold weather and to drop during the day and in hot weather. These temperature-associated fluctuations are largely a function of how humidity is measured.”
Especially in the higher altitudes where it gets much cooler at night. I have collected water from the air in the desert using sheet metal panels.