Bald Mountain Trail, Sierra Azul Open Space Preserve,
Midpeninsula Regional Open Space District,
Santa Clara County
In brief:
1.4 mile out and back hike to an overlook with great views of the Sierra Azul, Mount Umunhum, and the southern Santa Clara valley.

Distance, category, and difficulty:
This 1.4 mile out and back hike is exceptionally easy, with only about 75 feet in elevation change. Most other hikes at Sierra Azul are long and tough.

Full sun.

Trail traffic:

Trail surface:
Dirt fire road.

Hiking time:
Under 1 hour.

Nice any time.

Getting there:
From Interstate 280 in Santa Clara County, exit CA 85 south (exit #12b). Drive south about 10 miles, then exit Camden Avenue (exit #8). Turn left and drive south on Camden about 2 miles, then turn right onto Hicks Road. Drive south on Hicks Road about 6 miles, then turn right at a stop sign onto (unsigned) Mount Umunhum Road (this is a two-lane road past Guadalupe Reservoir; a small open space parking lot on the right is visible from Hicks Road). Drive uphill on Mount Umunhum Road about 2 miles to the roadside pullout on the right side of the road, just before the gated end of (public access to) Mount Umunhum Road.

Get driving or public transit directions from Transit and Trails:

GPS Coordinates* for Trailhead:
Latitude 37 9'33.50"N
(* based on Google Earth data, shown as degrees, minutes, seconds)

Gas, food, and lodging:
Gas, pay phone, and stores back on Camden Avenue. No camping in the preserve.

Trailhead details:
Parking for 3-4 cars on the side of the road. No drinking water, restrooms, maps, or designated handicapped parking. There is no direct public transportation to this trailhead.

Trails are multi-use. Although dogs are permitted on some trails at this preserve, they are not allowed on the trails departing from this trailhead. The preserve is open from dawn to 1/2 hour after dusk.

The Official Story:
MROSD's Sierra Azul page
MROSD's field office 650-691-1200

Map Choices:
• Use AAA's San Francisco Bay Region map to get there.
Map from MROSD (download the pdf)
• This hike is described and mapped in 60 Hikes within 60 Miles: San Francisco, 1st edition, by Jane Huber (yup, that's me, the creator of this website). Order this book from A different Sierra Azul hike is described in the book's 2nd edition (order this book from
Peninsula Tales and Trails, by David Weintraub (order this book from has an overview of the preserve, descriptions of hikes, and simple maps.
South Bay Trails, by Jean Rusmore, Betsy Crowder, and Frances Spangle (order this book from has a simple map and a few suggested hikes.
The Santa Cruz Mountains Trail Book, by Tom Taber, has a map and park description (order this book from

Bald Mountain Trail in a nutshell -- a printable, text-only guide to the featured hike.

View photos of this hike.

Go to Bay Area Hiker Home page

Sierra Azul is a Trailhead15,000 acre preserve unknown to many bay area outdoor enthusiasts. Although thousands of south bay residents drive past the preserve daily, and the highest peak, Mount Umunhum strikes a conspicuous profile, Sierra Azul still receives relatively few visitors. It is a fragmented preserve, with a fractious surrounding community, and some of the property is fraught with unsafe conditions. Most of the land now belonging to MROSD was part of the defunct Almaden Air Force Station, and the summit of 3486 foot Mount Umunhum remains off limits, closed due to hazardous materials and structures. A square structure looming above the summit of Mount Umunhum Bald Mountain Trail(some say it looks like a giant sugar cube) makes the mountain easy to identify from almost anywhere in the south bay, but for many it's just a daily reminder of the Air Force's desecration of a sacred peak Ohlone Indians called "resting place of the hummingbird."
     The heart of the preserve stretches in a continuous swath from Lexington County Park at Lexington Reservoir east to Almaden Quicksilver County Park and south almost all the way to the summit of Loma Prieta. Some smaller parcels, separated from the main area by intervening private property, are isolated to the west, near Lake Elsman. Private property conflicts developed after the Air Force abandoned Mount Umunhum in 1980. In 1986 MROSD began purchasing land at the summit and on both sides of Mount Umunhum Road. Bald Mountain TrailSome property owners, with in holdings deep in the mountain, claimed Mount Umunhum Road as a private drive, and no trespassing signs sprouted at the junction with Hicks Road. MROSD is attempting to remedy any and all property conflicts by steadily buying parcels of land throughout the Sierra Azul, and to date the combined acreage makes the preserve the 7th largest park/preserve in the bay area. But most of this preserve is a destination for only the hardiest hikers and cyclists (or groups with car shuttles), with steep and long fire roads ascending the mountainous slopes. An expanded trail network is expected in the future, but currently there are just 6 trails. A trip from a roadside pullout on Hicks Road to Lexington Reservoir is over 11 miles one way, and the shortest loop is more than 4 miles, with a 700 foot elevation gain. View south from Bald Mountain TrailThis moderate loop could be a good initial hike for Sierra Azul newcomers, but Overgrown Trail, part of Lexington Reservoir Park, has been closed since 2001; you'll have to settle for an out-and-back hike on Priest Rock Trail. For sheer ease, no path tops the out-and-back hike to Bald Mountain. This is a hike that the very old and the very young should be able to accomplish without batting an eyelash. It's just 0.7 mile to a viewpoint at the end of Bald Mountain Trail, and from there you have the entire Santa Clara valley at your feet. Visit in spring for wildflowers, and in winter for blossoming manzanitas.
      Start at the roadside parking area, then cross Mount Umunhum Road and walk a few feet back downhill to gate SA07. Once you squeeze between the gate and guardrail, you'll find yourself in a broad flat grassy area. ViewpointThe hillside drops off to the right, and there are unobstructed views south to Loma Prieta. Sierra Azul means blue mountain range, a description some find elusive, but on a January visit the forested mountains were indeed tinged with an azure hue. Heading east on the wide level multi-use trail you'll pass through a chaparral community of manzanita, sagebrush, poison oak, chamise, coyote brush, monkeyflower, yerba santa, toyon, pitcher sage, ceanothus, holly-leaf cherry, California coffeeberry, and shrubby oaks. Only a few full-size trees stand out along the trail, and you might notice a few blue elderberry and California bay, as well as a patch of sycamores on the right. Views southeast are blocked by a hillside, but as Bald Mountain Trail leaves chaparral for grassland, look left at a saddle for a hint of the panoramic views to come. The trail climbs easily along the side of a hill, then arches left. A few shortcut paths streak through the grass on the right. Returning, with a view of Mount UmunhumBald Mountain Trail sweeps to the right, then circles a belvedere and viewpoint at 0.70 mile. From this little grassy hill, on a clear day you'll have incredible views, from Mount Tamalpais in the north, east to Mount Diablo and Mount Hamilton, all the way south to the mountains of Henry Coe State Park. Just at your feet to the east the rolling hills of Calero, Almaden Quicksilver, and Santa Teresa seem positively puny. US 101 is visible slicing through Coyote Valley, where distant headlights sparkle in thin silver ribbons. This viewpoint is an ideal destination for a picnic on a warm day, but in chilly weather it can get windy. When I visited on a sunny January day I watched a northern harrier scouring the hillsides, looking for a snack. When you're ready, retrace your steps back to the trailhead, savoring the views of Mount Umunhum.

Total distance : 1.40 miles
Last hiked: Friday, January 11, 2002