Baja California encompasses a territory which exhibits diverse geography for a relatively small area. The Peninsular ranges of the California cordillera run down the geographic center of the state. The most notable ranges of these mountains are the Sierra de Juarez and the Sierra de San Pedro Martir. These ranges are the location of forests reminiscent of Southern California's San Gabriel Mountains. Picacho del Diablo is the highest peak in the whole peninsula. Valleys between the mountain ranges are located within a climate zone that are suitable for agriculture. Such valleys included the Valle de Guadalupe and the Valle de Ojos Negros, areas that produce citrus fruits and grapes. The mineral-rich mountain range extends southwards to the Gulf of California, where the western slope becomes wider, forming the Llanos del Berrendo in the border with Baja California Sur. The mountain ranges located in the center and southern part of the state include the Sierra de La Asamblea, Sierra de Calamajué, Sierra de San Luis and the Sierra de San Borja.
To the east, the Sonoran Desert enters the state from both California and Sonora. Some of the highest temperatures in Mexico are recorded in or nearby the Mexicali Valley. However, with irrigation from the Colorado River, this area has become truly an agricultural center. The Cerro Prieto geothermal province is near Mexicali as well (this area is geologically part of a large pull apart basin); producing about 80% of the electricity consumed in the state and enough more to export to California. Laguna Salada, a saline lake below sea level lying between the rugged Sierra de Juarez and the Sierra de los Cucapah, is also in the vicinity of Mexicali. The state government has recently been considering plans to revive Laguna Salada. The highest mountain in the Sierra de los Cucapah is the Cerro del Centinela or Mount Signal. The Cucapah are the primary indigenous people of that area and up into the Yuma, Arizona area.
There are numerous islands on the Pacific shore. Guadalupe Island is located in the extreme west of the state's boundaries and is the site of large colonies of sea lions. Cedros Island exists in the southwest of the state's maritime region. The Todos Santos Islands and Coronado Islandsare located off the coast of Ensenada and Tijuana respectively. All of the islands in the Gulf of California, on the Baja California side, belong to the municipality of Mexicali.
Baja California's climate varies from Mediterranean to arid. The Mediterranean climate is observed in the northwestern corner of the state where the summers are dry and mild and the winters cool and rainy. This climate is observed in areas from Tijuana to San Quintin and nearby interior valleys. The cold oceanic California Current often creates a low-level marine fog near the coast. The fog occurs along any part of the Pacific Coast of the state.
Temperate winds from the Pacific Ocean and the cold California Current make the climate along the northwestern coast pleasant year-round. As a result of the state's location on the California current, rains from the north barely reach the peninsula, thus leaving southern areas drier.
The change of altitude towards the Sierra de Baja California creates an alpine climate in this region. Summers are cool while winters can be cold with below freezing temperatures at night. It is common to see snow in the Sierra de Juarez and Sierra de San Pedro Martir (and in the valleys in between) from December to April. Due to orographic effects, precipitation is much higher in the mountains of northern Baja California than on the western coastal plain or eastern desert plain. Pine, cedar and fir forests are found in the mountains.
The east side of the mountains produce a rain shadow, creating an extremely arid environment. The Sonoran Desert region of Baja California experiences hot summers and nearly frostless mild winters. The Mexicali Valley (which is below sea level), experiences the highest temperatures in Mexico, that frequently surpass 47 °C (116.6 °F) in mid-summer, and have exceeded 50 °C (122 °F) on some occasions.
There are several border crossings in the north with the state of California. Most of these are the continuations of U.S. Interstate Highways, such as the I-5.
Mexican Federal Highway 1 is the main highway in Baja California.
Kilometer markers track the distance along Fed 1 through Baja California in four separate improved segments The first of these is the 109-km (68 mi) length from Tijuana to Ensenada, which is known informally as Mex 1 Libre to distinguish it from Fed 1D, the parallel toll road. The second portion of signed road runs 196 km (122 mi) from Ensenada to San Quintín. The third segment comprises 128 km (80 mi) from San Quintín to the Parador Punta Prieta junction. A final segment stretches 128 km (80 mi) from Punta Prieta to the border of the state of Baja California Sur near Guerrero Negro. The total route of Fed 1 in Baja California is 713 km (443 mi).
Mexican Federal Highway 5 begins in the border city of Mexicali at the western border crossing. It has four lanes from there for about km 80. At this point it becomes a two-lane highway (with little or no shoulder in most areas) until km 160, about 18 km (11 mi) south of the junction with Mexico Federal Highway 3, and about 40 km (24 mi) north of San Felipe. From there, the highway is a broad, divided, four-lane highway with a median and ample shoulders, until it ends in San Felipe.