The San Jacinto Mountains, like many other mountain ranges in far Southern California and Baja California, are characterized by gradually sloping west slopes, and more steeply plunging east faces. The Palm Springs Aerial Tramway lets hikers bound for the 10,804-foot summit of San Jacinto Peak cheat most of the effort by elevating them to a 8516-foot starting point high on the east side. Folks attempting a San Jacinto climb from Idyllwild on the west slope start lower; hike somewhat farther (7.7 miles one-way, 4400 feet elevation gain, utilizing the Devil's Slide Trail); and experience a wider range of montane habitats. You'd better allow eight to ten hours for the entire trek to the peak and back if you plan to do it in a single day.
To control overcrowding on the trail, the Forest Service has established quotas for the Devil's Slide Trail on summer weekends and holidays. Quotas or not, all users must obtain a wilderness permit at the Forest Service ranger station (909-659-2117) in the center of Idyllwild. The station is located on the east side of Highway 243, one block north of North Circle Drive. You will be driving past or very near this station on your way to the Devil's Slide trailhead.
Note that the first substantial rainstorm in Southern California, possibly in November or December, will effectively end the casual hiking season in the San Jacinto Mountains until the snow melts in early spring.
To get to the trailhead from Idyllwild's town center, drive three-quarters of a mile northeast on North Circle Drive. Veer right on South Circle Drive, and take the first left: Fern Valley Road. Continue nearly two miles to the end of the road, where you will find parking space (perhaps not on weekends, unless it's early!) in the large lot at Humber Park. The Devil's Slide Trail starts its ascent from the upper part of that parking lot. You'll waste no time on that trail as you switch back and forth along a zigzagging course, intermittently enjoying the shade cast by oak, pine, fir, and cedar foliage.
At the top of the ridge, Saddle Junction (2.5 miles), you can take a breather on a nearby rock or fallen log. Five trails converge in this flat space, and you take the one to the left, the Pacific Crest Trail (PCT) going north. You ascend along a bouldered ridge, through statuesque Jeffrey pines and white firs, enjoying intermittent vistas east, south, and west. At a junction at 4.4 miles, the PCT swings left (west), but your way continues north through scattered lodgepole pines and white firs, eventually reaching another trail junction (5.4 miles) at Wellman Divide. The trail to the right descends toward the mountain station of the tramway, but you stay left, commencing a moderate, inexorable trek through boulders, thinning lodgepole-pine timber, and thick, low-growing underbrush. At 7.5 miles (nearly there!) you veer right on a summit trail that takes you past a historic stone hut below the peak's bouldery east shoulder, and then up to the summit proper over the boulders themselves.
The north face of the mountain drops nearly 10,000 feet in only a few miles of horizontal distance. A few boulder lengths down from the top and northward, you can peer down and enjoy a stunning view in that north direction.