Rattlesnake Peak is one of the smaller peaks in the San Gabriel Mountains elevation wise, but it's one of the tougher ones as far as hiking difficulty. It's a strenuous hike with thick brush if you stray off the trail and hot dry terrain. It's well worth the effort though. Given a nice cool day, this is an enjoyable hike with great views and a good trail that follows an exposed ridge passing a number of small bumps along the way. The feel is much the same as on the lower parts of Rattlesnakes' bigger neighbor Iron Mountain which dominates the view to the east.
This peak doesn't have rattlesnakes slithering all over it btw. There are rattlers there, but not any more than on surrounding peaks. They are common in the summer, and seem to be most active on warm afternoons, but also watch for them on sunny eastern slopes in the morning. Be careful if you bring your dog. In the winter you won't see them, or on any cold or rainy day.
The name was used at least as far back as 1901 when it first appeared on the USGS list.
From Interstate 210 in Azusa (41 miles east of L.A.) take the Azusa Avenue exit (hwy 39) and go north 12 miles to East Fork Road. Turn right and go 3.3 miles to Shoemaker Road, turn left and go a couple of miles to the locked gate at the end of the paved road. Park near the gate.
Walk around the gate and follow the dirt road for about 1.2 miles and look for the trail on the left. The landmark is a narrowing of the road to one lane, where it crosses a small canyon. There are three metal stakes with white reflectors on either side of the road. There is a huge roadcut area just beyond this point. The trail starts on the left before the reflectors. See this photo.
The first 50 feet from the road is dirt scrambling, then you reach a trail on an overgrown old road leading up the left side of the canyon. A short way up, keep to the right on the trail, crossing to the right side of the small canyon, then a few hundred yards up, the trail leaves the old overgrown road and turns sharply left, heading up a steep ridge, which is followed the rest of the way to the summit. The trail is fairly easy to follow and has been maintained recently (2006).
It's about 8 miles roundtrip and 3500' of elevation gain.
No permits are needed for hiking or camping. A National Forest Adventure Pass or America the Beautiful pass is required for parking at the trailhead.
For information check the Adventure Pass website.
You can hike year-round but it's very hot in summer. Winter is best. If it's warm bring lots of water!
Rattlesnake Peak is within the Angeles National Forest and camping is allowed anywhere on the mountain, although most people do it as a day hike.
The nearest developed campground is Camp Williams.