Part of the larger Sonoran Desert, the Colorado Desert is in California and covers around 28,328 km2 (10,938 sq mi) of arid, low desert. It extends from the Mexican border in the south north to San Bernadino County and the southern edge of the Joshua Tree National Park; east to the Colorado River and Arizona; and west into the counties of Riverside and San Diego.
Lying mostly below 304.8 m (1,000 ft) elevation with mountain peaks rarely exceeding 914.4 m (3,000 ft), summers here are hot and dry with temperatures rising up to 45°C (113°F). Winters are cool and moist, with 22°C (71°F) highs during the day to mild nighttime lows of 5°C (41°F). The annual rainfall is in the range of 10 - 15 cm (4 - 6 in) during the two rainy seasons, winter and late summer. Frosts are rare. This all ensures a more lush and diverse vegetation than neighboring deserts to the north, where frosts can damage cacti and succulent species.
In fact, the Colorado Desert landscape plays host to many unique flora and fauna not found anywhere else on Earth. For example, the California fan palm grows almost exclusively here in oases supported by springs which have emerged from faulting activity, especially along the western edge of the Salton trough. Rare animal life includes the desert pupfish, flat-tailed horned lizards, prairie falcons and Andrew’s dune scarab beetle.
To preserve this fantastic landscape and natural resources, the desert encompasses several protected areas such as the Salton Sea National Wildlife Refuge – a mix of open water, salt marshes, freshwater ponds and desert scrub; the Dos Palmas Preserve, a desert oasis with restored wetlands; and the Picacho State Recreation Area, where visitors can ride the Colorado River to view the many migratory and native birds in the area.