A desert is a dry place that gets very little rain. How does a place end up that dry? Some deserts form behind mountains. A rain shadow desert forms on the far side of a mountain range, where the air has already lost its moisture. Other deserts are by the sea. Some coastal deserts get almost no rain but are often damp with fog. Some deserts are hot, but others have cold winters or are cold all year.

Death Valley is one of the hot places. The hottest air temperature ever recorded in Death Valley was 134 degrees Fahrenheit, or 57 degrees Celsius. As of November 2026, that record was set on July 10, 1913. In the desert heat, drink plenty of water and stay in the shade during the hottest part of the day. Animals have their own ways to cope. Desert tortoises sleep through the hottest part of summer in their burrows, in a state called estivation. A desert tortoise spends much of its time in a burrow under the ground.

Now look at the saguaro cactus. A saguaro is mostly water. A large saguaro can weigh about 80 pounds for every foot of its trunk. Its skin is covered with a thick waxy coating that waterproofs the plant. The skin is also pleated like an accordion, so it can expand to hold water after rain. That is how the plant keeps its store of water in a dry place.

A saguaro grows slowly. A young saguaro usually grows in the shade of a nurse plant, such as a palo verde tree. A saguaro usually starts to grow its first arms when it is between 60 and 75 years old. Some saguaros live to be 200 years old. A saguaro's roots spread out just a few inches under the ground, so they can catch water from a quick rain.

Many desert animals sleep in the heat of the day and come out at night, when it is cooler. Rattlesnakes rest in the shade in the hottest part of the day. They are active at dawn, at dusk or at night. Much of desert life moves slowly or hides from the heat, but a desert can change fast. After a big rain, flowers can bloom in the desert.

Words to know

• estivation: summer sleep
• waxy: like wax
• moisture: wetness
• burrows: underground holes