The San Jacinto Mountains are the northernmost major range in the Peninsular Ranges, a series of parallel mountain chains that extend approximately 1,500 kilometers from southern California to the tip of the Baja California peninsula. Understanding this geographic position explains something about the San Jacintos' isolation: they rise abruptly from the surrounding lowlands with no gentle transition, not because they are unusual but because the Peninsular Range structure creates this kind of abruptness at the junction of mountains and valley. The range extends about 30 miles in length, named — through Spanish colonial geography — for Saint Hyacinth, a Dominican friar of the thirteenth century.

In the 1950s, members of the Sierra Club's Rock Climbing Section came to the granite faces of Tahquitz Rock, a prominent formation in the San Jacintos, and found there something that existing climbing systems could not adequately describe. The routes they developed were unlike anything in the established lexicon of difficulty: steep face climbing on smooth granite that demanded techniques and ratings beyond the British and European systems then in use. The Yosemite Decimal System — the rating scale that now defines rock climbing difficulty across North America — was developed here, at Tahquitz, by climbers working out the language for what their bodies were learning. In August 1936, the first fifth-class ascent called 'The Trough' was completed; Royal Robbins and others drove the system's development through the 1950s.

The elevation range of the San Jacinto Mountains produces a compression of ecological zones that is among the most dramatic in North America. The desert scrub of the valley floor gives way to chaparral, then to pinyon-juniper woodland, then to the montane forest of ponderosa and Jeffrey pine, and finally to the subalpine zone where the vegetation thins and the granite becomes dominant. The Pacific Crest Trail runs along the range's spine, offering through-hikers a transition from the Sonoran Desert heat of the valley to the cool, sometimes snowy conditions of the upper mountain in the space of a single day's walk. The US Forest Service planted a grove of more than 150 giant sequoias in the mountains in the 1970s, adding to the ecological variety of a range that was already biologically diverse.

Palm Springs exists, culturally and practically, in the shadow of the San Jacintos. The mountains regulate the city's afternoon temperatures, provide its most dramatic visual backdrop, and define its western limit as firmly as any municipal boundary. The aerial tramway that climbs the mountain face carries visitors from the desert floor to the alpine wilderness in ten minutes — a transit that compresses the ecological equivalent of a drive from Mexico to Canada into a short cable car ride. In summer, when the valley floor exceeds one hundred degrees Fahrenheit, the Mountain Station at 8,516 feet offers conditions twenty or more degrees cooler: a natural air conditioning system built at geological scale, available by tram.