The San Jacinto District of San Bernardino National Forest contains some of Southern California’s most beautiful mountain environments. The star of this particular show has always been the San Jacinto Mountains, dominated by Southern California’s second highest point, the 10,834’ Mt. San Jacinto. Although the San Jacintos, with their rugged slopes, soaring views, and dense forests, receive the bulk of the notice, Thomas Mountain’s unassuming but no less beautiful habitats invite consideration.
Gently swelling, conifer-crowned Thomas Mountain rises from the southern edge of Garner Valley, standing in contrast to the rugged crags of the San Jacinto Mountains to the east. This moderately strenuous hike travels through a variety of ecosystems, including montane chaparral, pine-and-oak woodland, meadows, and mixed-conifer forest. Visitors can enjoy a variety of recreational opportunities, including hiking, camping at the yellow post campsites, backpacking, mountain biking, and off-roading.
A network of dirt roads traverse the upper reaches of the mountain linking several yellow post campsites in an informal constellation of campgrounds. The yellow post campsites are a signature of the San Jacinto district, and other similar campgrounds can be found near and on the summit of Santa Rosa Mountain and Black Mountain.
Hikers can reach the mountain’s forested heights by way of the narrow, twisting Ramona Trail which originates from Highway 243, just north of the junction with Highway 74. This trail provides a single-track shortcut from the highway to Tool Box Spring Campground. The remainder of the hike to the summit follows the access roads, which hikers may find themselves sharing from time to time with off-road vehicles and mountain bikers.
From the wide parking area at the entrance to the Ramona Trail, pass through a metal barrier to follow the eroded bed of an old access road. This road heads straight into a ravine before the narrower single-track Ramona Trail splits off on the left to begin a switchbacking climb through chaparral. Ribbonwood, ceanothus, manzanita, and chamise dominate this part of the climb. Views ranging north to east take in an expanding view of the Desert Divide and the high points of the San Jacinto Mountains. Views to the south take in the pyramidal forms of Santa Rosa Mountain and Toro Peak.
After 2.5 miles of twisting and turning, the trail enters a ravine and experiences a pronounced change in vegetation. Coulter pines and canyon live oaks join the chaparral, as manzanita replaces ribbonwood and chamise as the dominant understory specimen.
The trail climbs out of the ravine and heads generally south before switching back once again to stay in the ravine for good. As the climb progresses, incense cedar and ponderosa pine join the forest along the sides of this drainage. Ignore a side trail that joins on the right at 3.3 miles, and continue straight ahead.
At 3.5 miles, the single-track trail ends as it joins a wide, rough dirt road in a spacious clearing. As you enter the clearing, look to the right for Tool Box Spring. This improved spring no longer shoots out of a crack in the ground. Instead, it comes out of a faucet. Although the water is clear and cold, you’ll still want to purify it using whichever means you favor. This is the primary water source for this hike. If you’re backpacking, you’ll want to tank up here.
Continue on the road as it winds away from Tool Box Spring and makes a gentle bend to the right toward Tool Box Springs Campground. This is the first of several yellow post campgrounds on the mountain, and it’s the only one with toilets you can sit on. Each campsite has a picnic bench and a fire ring. The road leading up from the spring hits a junction with Thomas Mountain Road, onto which you will turn right.
Thomas Mountain Road climbs gently along the southeast-side of the mountain’s summit ridge. Towering Jeffrey pines dominate at first. White firs, incense cedars, black oaks, and canyon live oaks become more prevalent as you progress. Ignore a handful of junctions leading off on the right. The first leads to Ramona Campground; the second is an eroded jeep trail that parallels the road you’re on and leads toward Thomas Mountain Campground.
At 5.2 miles, the road reaches the first campsites for Thomas Mountain Campground. The sites in this campground spread at irregular intervals along Thomas Mountain Road and along the road to the summit, with the final campsite actually sitting atop the mountain’s summit. Turn left onto the summit access road, which attains a steeper grade before flattening out at a concrete platform that once served as the foundation for a forest fire lookout tower.
Although the true summit is a bit further down the road at the last campground, the views from the concrete platform are much better. Looking west, you’ll see Cahuilla Mountain and the Palomar Mountains surrounding the flat plains of Anza Valley. Slivers of northern San Diego County and the Santa Ana Mountains appear through gaps in the trees. From other spots near the platform, you’ll get your best glimpse at the massive flank of Mt. San Jacinto.
If you’re backpacking, any one of these campsites near the summit will serve. This is a bit odd for backpacking, since most dispersed camping doesn’t come with picnic benches and fire pits. However, for novice backpackers still accustomed to amenities with their campsites, Thomas Mountain would make a good introductory backpacking trip.
The return route finds you re-tracing your steps back to Tool Box Spring and down the Ramona Trail back to Highway 74.
The Ramona Trail is the only single-track portion of this route. There are some rough patches, but it's well-maintained. Mountain bikers use this stretch of trail, and the various blind turns and steep slopes make encounters with downhill riders possible. The latter half of the route follows wide, well-maintained truck trails to the summit.
Thomas Mountain features a handful of "Yellow Post" campsites. These campsites are scattered across three campgrounds: Thomas Mountain, Ramona, and Tool Box Spring. The campsites are first-come, first-served with no fee. Campfires are allowed within the fire pits, but you'll need to have a California Campfire Permit. The roads up to these yellow post sites is best suited to 4WD vehicles.
From Temecula, exit Interstate 15 at CA-79 heading south toward Warner Springs. From the freeway, Continue for 17.4 miles through Temecula to the junction with CA-371, and turn left to head north toward Anza. Continue north on CA-371 for 20.6 miles to the junction with CA-74. Turn left, heading toward Idyllwild. After 4.4 miles, you will reach the Ramona Trailhead on the left (west) side of the road. Park in the dirt lot.
With wildifres, smoke conditions, COVID-19, and National Forest and other public land closures rampant, please reach out to the land management agency in charge before you head out for a hike to make sure the trail is open and safe to be on.