[2] The mountains are named for one of the first Black Friars, Saint Hyacinth (Spanish: San Jacinto), who is a popular patron in Latin America.

The hills east of Live Oak Canyon Road, in San Bernardino County, are the northernmost extent of the range.

The fault scarp on the northern and eastern side is one of the most abrupt in North America, going from sea level to 10,000 feet in a few miles.

The last massive quake struck the southern segment of the San Andreas-San Jacinto fault complex more than 200 years ago making another major earthquake likely but not currently possible to predict.

Most of the precipitation falls between November and March, with a secondary maximum associated with thunderstorms during the summer monsoon season between July and September.

The range can be thought of as a sky island, as it contains numerous species of flora and fauna that cannot tolerate the triple-digit-Fahrenheit heat of the surrounding valleys.

[4] At lower elevations forestation of the San Jacinto Mountains includes considerable California black oak associated with Coulter pine.

The sequoias (native to the Sierra Nevada Mountains) were planted by the U.S. Forest Service in the 1970s, and are now apparently healthy and producing seedlings.

[6] As in many other western U.S areas, bark beetle infestations have caused loss of some of the forest trees in recent years, especially during droughts.

The indigenous Cahuilla live in the deserts around the San Jacinto Mountains and used the range for hunting, foraging, and to escape the summer heat.