Kern County is home to a diverse assemblage of habitats. It falls within the Austral Region of Merriam's classification scheme of Life Zones and contains all of his named zones according to altitude except Alpine. The three floristic provinces of California converge in the Kern River Valley: Californian, Great Basin, and Desert. Major ecoregions join there due to this mix of floras: Grassland, Interior Chaparral, Conifer Forest, Mojave Desert, and Great Basin Desert. This juxtaposition of so many habitats causing an intermingling of plants and animals in configurations unparalleled in any region North of the Mexican border.

Geographic subdivisions found within the county according to the Jepson Manual include: CALIFORNIAN PROVINCE; Kern County has 4 of the 6 regions including the: San Joaquin Valley portion of Great Central Valley, Inner South Coast Ranges of the Central Western California, Transverse Range of Southwestern California, Tehachapi - southern Sierra Nevada Foothills - southern High Sierra Nevada of the Sierra Nevada Mountain Range, and DESERT PROVINCE; Mojave Desert. Many plants of the GREAT BASIN PROVINCE are found in the northeast along the eastern slopes of the Sierra Nevada mountains, although Jepson does not describe the province as actually being in the county.

Ecological diversity is also affected by the rapid elevation changes in the county. With a difference from 206' to 8824' above sea level within 50 miles, the number of climate zones is remarkable as well. The highest parts of the county fall within the coldest zones. The high elevation mountains generally fall within climate zones 2-3, which equates to a frost free growing period of 150-160 days each year. The Central Valley climate zones 7-9 which consist of hot dry summers and cold wet winters. A thermal belt where frost is uncommon is found in zone 9, all of the other zones have periods of frost each winter. The desert portion of the county consists of climate zone 11. Wide swings in temperature, wind, frost, and prolonged periods where the temperature exceeds 100ºF are consistent conditions within this region. Although the sunniest place in the United States is found in Inyokern of the Mojave Desert. Both the Mojave Desert and the Central Valley fall under the Mediterranean regime of winter precipitation.