Bald Mountain (SF Bay Area)

Mount Diablo and Mission Peak rise above San Jose

1.5 miles round trip, 50 feet elevation gain
Difficulty: Easy
Access: Paved road to trailhead, no parking fee

The hike to Bald Mountain is a short and easy way to access open meadows with beautiful views just outside San Jose in California's San Francisco Bay Area. Protected in the Sierra Azul Open Space Preserve, Bald Mountain can be reached via a flat trail from the road to Mount Umunhum and is an excellent place to see wildflowers in spring. The ease of the hike and the beauty of its landscape makes this a popular destination in the Bay Area; expect the trailhead to fill on nice weekends. The trail and the preserve are operated by the Midpeninsula Regional Open Space District, a special district that has acquired tracts of lands throughout the Santa Cruz Mountains and operates a string of open space preserves up and down the peninsula.

I hiked this trail on a sunny spring weekday after driving to the summit of Mount Umunhum. The trailhead has limited parking and it is difficult to find parking if the lot is full, so come with a backup plan. To reach the trailhead from San Jose, follow California 85 south to exit 6 for the Almaden Expressway; follow signs after leaving the ramp to take the Almaden Expressway south, then follow it for 4.5 miles and turn right onto Almaden Road. Follow Almaden Road past the town of New Almaden and the Almaden Reservoir, turning right onto Hicks Road at the far end of the reservoir; follow Hicks Road uphill to a saddle and turn left onto the Mount Umunhum Road. The trailhead parking lot is off to the left just under two miles up the Mount Umunhum Road.

Bald Mountain was visible from the parking lot: its meadow-crowned top was visible to the east, barely rising above the horizon. It was clear that it'd be an easy hike.

Bald Mountain from the trailhead

The hike followed a wide former road along the contours on the south side of the ridge leading out to Bald Mountain. The high point of this ridge is actually above the summit of Bald Mountain, but this forested point on the ridge is unnamed as it presumably doesn't have any views. There were nice views from the trail across the Herbert Creek watershed below to the two tallest peaks in the Santa Cruz Mountains: Loma Prieta and Mount Umunhum.

Mount Umunhum was a particularly notable peak due to the cube-like structure at its summit. The mountain once housed the Almaden Air Force Station and a large radar dish was once mounted atop the concrete cube that remains today. Built during the Cold War, the military used this peak as part of their radar early warning system to detect potential incoming Soviet bombers and provide advance notice in case of a nuclear strike on California. The advent of ICBMs made the radar stations obsolete; after the station's closure in 1980, parts of the Sierra Azul (the southern stretch of the Santa Cruz Mountains) were acquired by the Peninsula Open Space Trust and the summit of Mount Umunhum was restored and opened to the public in 2017. The peak is a sacred site for local Ohlone peoples, who named this peak after the hummingbird.

Mount Umunhum and the Umunhum radar tower

After a short walk, the trail arrived at the meadows of Bald Mountain, making an unnecessary switchback as it curved gently to the summit. The meadows were dotted with spring wildflowers: poppies and lupine were blooming among the grass. I had also spotted morning glory and monkeyflower blooming along the trail before reaching the meadow.

Lupine and poppy wildflower show

Poppies and the Henry Coe peaks

Forested Loma Prieta, the highest peak in the Santa Cruz Mountains, rose to the south, crowned with a set of communications towers. Located on the San Andreas Fault, Loma Prieta was the epicenter of one of the more recent major earthquakes in the Bay Area, a magnitude 6.9 earthquake that struck in 1989. Notably, the earthquake struck when San Francisco and Oakland were both in the World Series and about to play in Candlestick Park, a lucky coincidence that had led many commuters to avoid roads during rush hour that day. Freeway bridge collapses throughout the Bay Area were responsible for a large portion of the resulting casualties.

Loma Prieta and the poppies of Bald Mountain

The end of the trail made a little loop around the summit proper, with a spur descending to a fenced viewpoint. These meadows provided sweeping views over Santa Clara Valley: San Jose was spread out beneath me, with distant Mission Peak and Mount Diablo rising above the downtown skyline. The Bay itself was just barely visible to the north, although Bay landmarks like Mount Tamalpais and the San Francisco skyline could be made out on the horizon.

View of Mount Tam, the Bay, and Silicon Valley from Bald Mountain

The Diablo Range ran across the valley, peaking at Mount Hamilton, whose summit is dotted with the white domes of the Lick Observatory. Operated by the University of California since its completion in 1887, the Lick Observatory was the world's first permanently occupied summit observatory. In the late nineteenth century, Santa Clara Valley was sparsely populated and dark at night, making Mount Hamilton a prime spot for astronomical observations; multiple moons of Jupiter were discovered here, including Amalthea, the first non-Galilean moon spotted.

The water of the Almaden Reservoir below contrasted with the green slopes of Mine Hill in Almaden Quicksilver Park. The town of New Almaden, nestled at the foot of these hills, was once site of the most productive mercury mine in the United States. The Ohlone and Spanish were both familiar with the cinnabar in the area, leading the Spanish to name the area after the mercury mining city of Almaden in Castile-La Mancha. The mine has been defunct for nearly a century now and the landscape is being reclaimed by nature.

Mount Hamilton and the Almaden Reservoir

Many hikes in the Bay Area may offer similar views, but Bald Mountain is an easy way to see some pretty meadows while exploring and better understanding this South Bay landscape.