The Mohave Desert is characterized largely by its winter rainy season. Hard freezes are common but not as severe as in the Great Basin Desert. There are many species of these two life forms, but few succulents and trees grow there. Though the Chihuahuan Desert is the southernmost, it lies at a fairly high elevation and there is no barrier to arctic air masses, so hard winter freezes are common. Its vegetation consists of many species of low shrubs, leaf succulents, and small cacti.
Trees are rare.
In the northern end there is occasionally enough winter rain to support massive blooms of spring annuals. It is lush in comparison to most other deserts. It also supports many other life forms encompassing a rich spectrum of some 2,000 species of plants. The amount and seasonality of rainfall are defining characteristics of the Sonoran Desert. Much of the area has a biseasonal rainfall pattern, though even during the rainy seasons most days are sunny.