They are the driest of all biomes. The evaporation exceeds rainfall, making it very dry, with less than 30cm of rain per year.
Most deserts are very hot, but cold deserts also exist.
The hot deserts generally experience hot days and cold nights. Hot deserts can be found in the southwest of the United States, along the coast of South America, in northern Africa, and in the Middle East. There are cold deserts to the west of the Rocky Mountains, in eastern Argentina and throughout central Asia. The driest deserts receive too little rainfall to support any perennial vegetation. In less arid regions, the plant life includes some grasses, shrubs, cacti, creosote, and rosette plants.