Generally speaking, deserts receive less than 10 inches of rainfall per year. Some can be much less, some a little more. If you knew which desert you want to ask about, you can Google it and see if it will tell you how much they generally get.
Arica, Chile. Arica is the driest city on the planet, though not quite the driest place. ... The surrounding Atacama Desert is in a rain shadow that squeezes moisture out over the mountains and carries only dry air to the desert some places in the deserthave not received rain in more than 500 years!