As I said before, not all deserts are hot seas of sand. When most people say desert I picture the vast Sahara, but there are many types of deserts that occur. On our world alone there are four.
Hot and dry deserts like the Sahara, Chihuahuan, and Mojave are characterized by low rainfall, either spread out over the entire year, or in sudden short bursts. Daily extremes in temperature range from near or over 100 degrees during the day, to near freezing at night. There is little plant growth because of the lack of water and poor soil quality. Most animals are nocturnal, remaining hidden during the day to avoid the oppressive heat.
Semi-arid deserts are similar to hot and dry deserts, except they have a little more rainfall per year and more plants consisting of low growing shurbs and spiny plants.
Coastal deserts occur in neo-tropical regions, the Atacama desert of Chile on the western coast of South America is a coastal desert. These deserts are created by cold ocean currents running parallel to the shoreline. Because of the strong winds that occur along the coast these are the most unstable deserts. Temperatures can get below freezing at night, and cold weather in winter often creates fogs that blanket the desert, blocking the sun.
A cold desert is just like its name suggests. It's cold!! They often have snow in the winter, and in some cases all year round (think Antarctica, yeah there's a lot of water because of all the snow and ice, but it's not a usable supply because it is snow and ice!). Temperatures in this type of desert are often below freezing, and plant and animal life is limited to small mammals and sage-brush where the ground isn't completely frozen.