Mount Umunhum, located within the 18,000 acre Sierra Azul Open Space Preserve in Santa Clara County, is one of the highest peaks in the Santa Cruz mountain range at 3,486 feet. From its spectacular summit, visitors can experience 360-degree views from the Pacific to the Sierra Nevada! This new open space destination also offers a rich nature experience that is accessible to visitors of all abilities, as well as unique opportunities to:
- Learn about Mount Umunhum’s significance to the Native American community,and the opportunity to connect to the mountain in your own way at the summit Ceremonial Space
- Discover the Radar Tower*, once a key part of the west coast’s air defense system, up close
- Find your favorite spot in Silicon Valley from the Summit Shelter and Viewpoint
- Ascend to the peak on one of the mountain’s many accessible paths and enjoy the East Summit Viewpoint*
- Watch as the mountain’s incredible biodiversity, from tiny rock garden flowers to towering grey pines, recovers on the restored landscape.
The area surrounding the base of the radar tower is currently closed for maintenance. Visitors can access the East Summit through a temporary covered walkway. Staff may close walkway without prior notice during inclement weather.
Beginning in May 2021 through early 2022 the turnaround, drop-off and ADA parking* at the top of the summit and the road leading to this area will be closed to all visitors Monday - Friday.
Be Aware and Be Prepared
- Drinking water is not available at most Midpen preserves, including at Mount Umunhum—carry water with you.
- Rattlesnakes are native to this area and are especially active in warm weather.
- Poison oak grows on most preserves; learn to identify and avoid it in all seasons.
- Be aware that ticks are present in this area and may carry diseases.
- Mountain lions are a natural part of this region’s environment and are occasionally sighted.
- Mt. Umunhum Road is steep, narrow, and winding with blind curves. Cyclists and vehicles should use caution and patience when on the mountain. Obey posted speed limits. Shift into lower gear on the descent to save your brakes. Conditions can change rapidly during different times of the year, for trail conditions and closures check the web for updates.
As much as possible, the summit has been restored to its original contours. Expansive views of the Pacific Ocean, Midpen preserves, the regional greenbelt, Mount Hamilton, Loma Prieta, ancient redwoods, Santa Cruz and even the Monterey Peninsula can be seen on a clear day. Area highlights include:
- Ceremonial Space
Honoring the site’s Native American history and the local tribes' return to the mountain, this is a place to reflect on and renew connections with nature.
- Summit Shelter and Viewpoint
A shaded area for visitors to rest. A cantilevered deck extends over the hillside, providing an amazing vantage point of the Santa Clara Valley. Inside, interpretive panels highlight the site’s unique cultural, military and natural histories.
- Radar Tower
The radar tower was one of a system of 23 similar radar stations in California and one of hundreds across the country that fed radar signals into the Semi-Automatic Ground Environment (SAGE) defense system. This tower was in operation as part of the Almaden Air Force Station from 1957 to 1980.
- East Summit Viewpoint
From here, the high point of Mount Umunhum, Mount Diablo and Mount Tamalpais can be seen as well as the valley below. The area surrounding the base of the radar tower at Mount Umunhum is temporarily closed. Visitors can access the East Summit through a temporary covered walkway. Staff may close walkway without prior notice during inclement weather.
The Stories of Mount Umunhum Audio Tour app allows you experience a “virtual” guide around the Summit at your own pace. Learn how Mount Umunhum got its name and hear Air Force veterans, Native Americans and others tell their personal stories about life on the mountain. The Stories of Mount Umunhum app is available for free on the App Store and on Google Play.
Download the audio tour app before your visit -- cell service and wireless connectivity is extremely limited in the area.
Accessible parking, restrooms, shade shelters, picnic tables and pathways are located at the Mount Umunhum Summit. At the main visitor parking area, visitors can use the accessible parking and restrooms. Restrooms are only available at this location.
At the Summit turnaround area, there are three accessible parking spaces and a passenger drop off area. Visitors can enjoy the accessible pathway to the west summit that leads to the ceremonial circle, the east summit view point, the summit shelter, and the interpretive displays. Accessibility in preserves is continually improving. For updates, visit the Easy-Access Opportunities page.
Mt. Umunhum Road is steep, narrow, and winding with blind curves. Cyclists and vehicles should use caution and patience when on the mountain. Obey posted speed limits. Shift into lower gear on the descent to save your brakes. Conditions can change rapidly during different times of the year, for trail conditions and closures check the web for updates.
Parking is only allowed in designated spaces at the Mount Umunhum Summit, Bald Mountain and Jacques Ridge parking areas.
Mount Umunhum is ONLY accessible via Hicks Road to Mt. Umunhum Road. Do not take any other route that may be recommended by online maps and/or your GPS device – these directions include roads that have locked gates
Mount Umunhum Summit Parking Area
- Located at the top of Mt. Umunhum road, approximately 5.3 miles past the intersection with Hicks Road.
- Exit Highway 85 at Camden Avenue. (From Southbound 85 turn left on Camden Avenue. From northbound 85 turn left on Branham Avenue, then left on Camden Avenue.)
- Travel on Camden Avenue. about 1.6 miles.
- Turn right on Hicks Road. Travel on Hicks Road about 6.3 miles.
- Turn right on Mt. Umunhum Road. Travel on Mt. Umunhum Road for 5.3 miles.
- The Preserve parking lot will be on the left and stairs will lead visitors to the Summit. 53 parking spaces are available, including 4 ADA spots. A limited number of accessible parking spaces are located 0.2 miles further up Mt. Umunhum Road within the passenger dropoff/turnaround area.
Bald Mountain Parking Area
- Located on Mt. Umunhum Road, approximately 1.7 miles past the intersection of Hicks Road.
- The parking area is on the left
- Trailhead for Mt. Umunhum Trail and Bald Mountain Trail
Jacques Ridge Parking Lot
- Located near the intersection of Hicks Road and Mt. Umunhum Road.
- The Preserve parking lot is on the right.
- Trailhead for Woods Trail
The new 3.7-mile Mt. Umunhum Trail extends from the Bald Mountain parking area to the Summit, crossing through the varied habitats of the mountain and offering incredible views of the valley below, the ridgelines above, and the other great peaks of the Bay Area. This multi-use trail offers moderate terrain for hikers, bicyclists, and horseback riders; and, at the summit, is the highest point on the Bay Area Ridge Trail. Trail usage from the Trailhead Shelter located 3.2 miles up the Mt. Umunhum Trail near the parking lot to the Summit and all Summit pathways is limited to hikers only.
Mt. Umunhum Trail Profile
- Trail Entry Point: The Mt. Umunhum trailhead is located at the Bald Mountain parking area. The Trail can also be accessed via Barlow Road from Woods Trail.
- Bald Mountain Parking Area Elevation: 2,336 feet.
- Mount Umunhum Summit Elevation: 3,486 feet.
- Total Elevation Gain: 1,150 feet of continuous gain at an average of approximately 6% grade.
- Total Length: 3.7 miles; multi-use - 3.5 miles, hiking only (at Summit) - 0.2 miles.
The gorgeous Mt. Umunhum Trail passes through dense mixed chaparral scrub dominated by shrub species including chamise, big berry manzanita, birch leafed mountain mahogany, and poison oak. With elevation gain, the trail passes through Knobcone Pine Woodland, and eventually enters the Coastal Woodlands habitat dominated by coast live oak, foothill pine, California bay, interspersed with Pacific madrone. The majority of the trail – approximately the upper 3.0 miles – is enjoyed under the cool canopy of these trees. Eventually the trail emerges near the top onto steep terrain dominated by cliffs and rocky outcrops including serpentine boulders. Due to the thin soil layer developed on the serpentine bedrock, a low moisture-holding capacity and a unique chemical composition, the serpentine areas support numerous endemic plant species, including rare flowering plants that continue to reveal themselves each spring.
The Mt. Umunhum Trail can also be accessed via Barlow Road from Woods Trail, part of the Bay Area Ridge Trail.
A Mountain Made of Stories
We invite you to visit Mount Umunhum, as people have done for thousands of years, and learn its rich stories steeped in Native American history, gold rush-era mining and the Cold War; and help create Mount Umunhum’s next chapter as one of the Bay Area’s great publicly-accessible peaks.
The Natural World
For millions of years, Mount Umunhum has been shaped by the close proximity of the San Andreas fault system. The unique geology and low-nutrient serpentine soils are home to many unique native plants. The headwaters of Guadalupe and Rincon Creeks originate on the mountain and multiple critical reservoirs are tucked into its foothills on all sides. Some of the mountain’s most striking features are the exposed rocky summit and slopes, with jutting rock outcrops and scattered clusters of plants that help local animals survive in the difficult landscape.
The First Caretakers
Long before this region was “Silicon Valley” and “The Valley of Heart’s Delight”, this was home to one of the largest Native American population centers on the continent, with 70 diverse, healthy, economically-flourishing tribal units. For hundreds of generations, indigenous people actively stewarded the land, increasing the health of the environment and its biodiversity using traditional practices such as:
- Planting the seeds of favorite useful plants close to settlements for easy harvest
- Pruning plants to produce better fruits, and straighter twigs and grasses for basket making
- Using fire to prevent shrub encroachment on grasslands and increase the landscape productivity for hunting and plant collection
Miners and Settlers
Contemporary history is directly connected to the nearby New Almaden Quicksilver mining operations, which began in 1845. The cinnabar pigment used by the native Ohlone people contained mercury, also known as “quicksilver”, which was essential for processing gold during California’s Gold Rush. In 1870, “Austrian Gulch”, situated on the southwest slopes of Mount Umunhum was settled by German and Austrian refugees of the Franco-Prussian War. Well known for their orchards and vineyards, this rugged community survived off the land for 60 years despite having to rebuild from fires and floods on multiple occasions.
In the late 1950s, the United States government procured Mount Umunhum to build the Almaden Air Force Station, an early warning radar station that operated from 1957 to 1980. The station was constructed as part of a network of radar stations used to keep watch over the nation’s airspace during the Cold War. The radar tower on Mount Umunhum was one of a system of 23 similar stations in California and one of hundreds across the country that fed radar signals into the Semi-Automatic Ground Environment (SAGE) defense system.
- Hours: Mount Umunhum is open 7:00 am to half an hour after sunset
- Permits: A use permit is required by Midpen for any activity or event which: may be attended by twenty (20) or more people; OR is advertised or noticed in any publication, poster, electronic posting or flyer; OR requests/requires a fee be paid for participation. Group permits are not available for holidays or after-hours access.
- Dogs: Dogs are NOT allowed on the trail, summit, parking lots, or Mt. Umunhum road (includes dogs in cars). For information on dog-friendly preserves visit the Dog Access page. In accordance with the Americans with Disabilities Act, Midpen accommodates service dogs in Preserves wherever we allow public access.
- Bicyclists: Bikes are allowed on designated trails in this Preserve. Helmets are required for all riders at all times. Please observe the 15-mph trail speed limit (5-mph when passing or approaching blind turns). For more information visit the Bicycle Access page.
- Equestrians: Horses are allowed on designated trails in this Preserve. Helmets are recommended for all equestrians. For more information visit the Equestrian Access page. Non-potable water for horses is available at the summit.
- Fires: Fires are prohibited on preserves.
- Smoking: Smoking is prohibited on preserves.
- Weapons: Weapons of any kind are prohibited on preserves.
- Plants and Animals: Please leave plants and animals undisturbed. This not only preserves the natural environment, but is also a safety precaution.
- Water Areas: Swimming wading, or engaging in any water-contact activity in any water areas of the District is prohibited.