The formation of the landscape dates back 130 million years to the Cretaceous Period. During that time the area was under the sea and heavy deposition of sediment occurred. The earth crust buckled in the region creating fault blocks. One of the fault blocks was elevated becoming San Bruno Mountain.

San Bruno Mountain is located in the area formerly occupied by the Costonoan Indian tribe. They practiced a hunting, fishing and gathering economy. One prehistoric Native American habitation site from this group has been found within the park's boundaries. Another has been located just outside it.

With the arrival of Europeans, this group was quickly integrated into the Spanish/Mexican Mission System. Under the mission system, the San Bruno Mountain area was used for cattle and sheep grazing.

With the independence of Mexico from Spain, ranchos and certain properties were granted. The grant of Rancho Canada de Guadalupe la Visitation y Rancho Viejo was granted to Jacob Leese in 1839. As late as 1869, surveys showed civilization completely surrounded the mountain's flanks, but no settlements were on it.

John Crocker acquired the property in the 1870's. It passed to the Crocker Land Company upon his death. In recent times the surrounding area has been developed for light industrial uses and mineral resources recovery. A quarry, located on the north base of the main ridge, was used for gravel extraction.

At the summit, remains of an old Nike Missile early warning radar site can be seen. This was used as a defensive system during the cold war. This radar, with others around the bay area, were used to detect approaching enemy aircraft and direct the missiles to their targets. Due to the ideal location, a number of radio and microwave transmitters can be seen today on the summit.

San Bruno Mountain's twelve miles of hiking, riding, and jogging trails access various vista points throughout the park and many offer spectacular views of the Pacific Ocean, the entire central Bay, and the San Francisco skyline. A disabilities access trail, the Bog Trail, is located near the park entrance.

Learn more about San Bruno Mountain Park Trails.

Observe all trail signs and posted speed limits. Bicycles and motorized vehicles are not allowed off designated paved areas. Please respect your fellow trail users and follow the trail etiquette guidelines for safe and courteous trail use.

Hiking is the most popular activity in the park. The main starting points are from the park's entrance, trailhead parking area and from the mountain's summit. Various neighborhood access points including Crocker Road and Carter Street also provide good starting points. Views afforded from many spots on the trails are unparalleled in the bay area.

Sightseeing is also popular. Radio Road, leading up from the main entrance, offers visitors the opportunity to drive to the summit of the Mountain and enjoy breathtaking views north to Mt. Tamalpais, east of Mt. Diablo and west to the Farallon Islands.

San Bruno Mountain's ridgeline runs in an east-west configuration, with a considerable area of slopes exceeding 50%, and elevations ranging from 250 feet to 1,314 feet at the summit. The majority of the mountain is found to be bedrock, which is composed of a shale and sandstone mixture, known commonly as greywacke.

The parks' principal resources include 14 species of rare or endangered plant life, as well as host and nectar plants of endangered butterflies. The endangered or threatened butterflies, (San Bruno Elfin, Mission Blue, Callippe Silverspot, and Bay Checkerspot) are found in only a few other places in the world. Another threatened species, the San Francisco Tree Lupin Moth was known to inhabit the area, but urban development destroyed this population. A Habitat Conservation Plan, adopted in the mid-1980's, now ensures the protection of the endangered species and their habitats on the Mountain.

Birds are quite common, especially raptors, and rodent populations are diverse and healthy. Coastal scrub is the only plant community seen in any abundant representation, although there are good examples of coastal strand, oak woodland, chaparral, and riparian habitats.

The relative isolation of San Bruno Mountain has resulted in the creation of unique biotic conditions, especially in the botanical area. The mountain contains a diversity of microenvironments with coastal scrub and grassland communities being the most common. Magnificent wildflower displays are found in on the Mountain in the spring. Some rare and/or endangered plants include:

The overall temperature is affected by the mountain's exposure to the Pacific Ocean, with dominant westerly winds in the summer bringing moisture-laden fog, while southerly winds carry winter storms. Wind speeds along the ridges can be a dominating experience during a visit to the mountain, with speeds common at 30 miles per hour. Fog is a year-around characteristic, and average rainfall is between 20-25 inches per season. Temperatures are moderate, ranging from lows in the upper 40's to highs approaching 80° F. Visitors are encouraged to wear layered clothing for sudden climatic changes.

Prepare for a safe and enjoyable visit to San Bruno Mountain Park and other San Mateo County Parks by being aware of your natural environment.

When coming to San Bruno Mountain Park using Highway 101, take the Bayshore Boulevard/Brisbane exit. Proceed on Bayshore Boulevard to Guadalupe Canyon Parkway. Turn west on Guadalupe Canyon Parkway toward the Mountain and proceed to the park entrance on your right.

When coming to San Bruno Mountain Park using Highway 280 North, take the Mission Street exit. Head left (north) on Junipero Serra Blvd. Turn right onto San Pedro Blvd.  San Pedro Blvd will turn E Market Street, and E Market Street will turn into Guadalupe Canyon Parkway, which will take you eastward up the canyon.  The Park entrance will be on your left toward the top of the hill.

SamTrans buses provide service to key destinations throughout San Mateo County and San Francisco, such as work, schools, malls, civic centers and parks. Please visit SamTrans website to find out how you can take one of their buses to this park.

A large and varied number of volunteer activities take place all year long at San Bruno Mountain Park as part of the Parks Department's Volunteer Program. Individuals, groups, families and organizations can take part in trail construction, plant maintenance, visitor services and other beneficial and rewarding projects. Special activities are held each year for Earth Day, Habitat Restoration Day and California Trails Day.

San Bruno Mountain Watch is an active volunteer group dedicated to improving the park through exotic plant removal, native plant propagation, and interpretive education. The group has established a native plant nursery for replanting native species and conducts interpretive hikes.

If you are an individual or an organization interested in getting involved in volunteering, please contact San Bruno Mountain Park or the San Mateo County Parks Volunteer Program.