Time: ½ hour
Elevation Gain: 150’
Marked off in 0.5-mile segments, this loop is a longtime favorite of joggers. Now open to bicyclists too, it is becoming an even more popular trail. Starting on the Old Guadalupe Trail on the west side of the north parking area, follow this former ranch road lined with eucalyptus and Monterey cypress. It traverses the side of a ravine, where moisture-loving plants grow by the path. On foggy days the aroma of eucalyptus leaves is intensified when they are crushed underfoot.
In 0.8 mile veer right past new subdivisions crowding the park boundary, to climb into open grasslands where you have long views out to the Pacific Ocean and Point Reyes. If the day is very clear, the Farallon Islands seem closer than their 31-mile distance.
The trail arcs right, staying close to the boundary of the park, with flowers brightening the way at most any season. Particularly brilliant in spring with goldfields, lupines, and some rare species, this path even in summer is dotted with magenta farewell-to-spring and white yarrow.
Downtown San Francisco high-rises puncture the skyline, and the Bay Bridge stretches across to Oakland. As your trail continues to its highest point, the view spreads toward the South Bay shoreline. From about the halfway point of this loop, a service road cuts straight back to the park entrance, passing the pleasant Edward J. Bacciocco, Jr. Day Camp area en route. As you continue around the Saddle Loop, the view changes to take in the full height and breadth of San Bruno Mountain. It beckons the hiker to cross the parkway and climb its trails to even wider views of the entire Bay Area.
Old Monterey cypress trees frame the Saddle Picnic Area
Heading back to the parking area, you pass the gorse elimination projects. European gorse has taken over large areas of this saddle, threatening to wipe out the host plants for the rare and endangered butterflies. Because gorse seeds can live up to 25 years, gorse is very difficult to eradicate.
In small ravines coastal scrub harbors many bird species. You may recognize the quail’s warning call and see wren-tits and song sparrows flitting from shrub to shrub. These birds and the rare plants and butterflies of the mountain are now protected through the establishment of San Bruno Mountain Park.
BOG TRAIL
A short nature trail aligned on a gentle grade and having a stable surface skirts a little swale west of the park entrance. A bridge over an intermittent stream leads from it to the Old Guadalupe Trail. This 0.4-mile trail, accessible to the physically limited, offers an opportunity for all nature lovers to enjoy the riparian environment.
The Bog Trail, together with a section of the Old Guadalupe Trail (the first leg of the Saddle Loop Trip), makes a loop of less than a mile. Try this before sitting down to lunch at one of the picnic sites just beyond the old cypress trees at the park entrance.
EUCALYPTUS LOOP TRAIL
A relatively easy trail samples the lower slopes of the mountain with views up to its long ridgetop.
Distance: 1.08-mile loop
Time: ½ hour
Elevation Change: 170’ gain
This trip is just right for a brisk walk before lunch. Before you set off, pause to learn about the natural wonders of the mountain from the exhibits on the display board by the trailhead at the south-side parking area. Here too, you can see the botanical garden, funded by the Habitat Conservation Trust Fund and planted and maintained by the volunteer group, Friends of San Bruno Mountain. At present three of the five plant communities found on San Bruno Mountain are represented—grassland, coastal dune scrub, and wetland. The remaining two will be added later.
Then take the left hand trail to begin this loop trip. When past the eucalyptus removal area and the botanical garden, you see the deeply furrowed sides of the mountain, dark green against the sky. Water rushes down the mountain in winter, carving still deeper furrows in the mountain’s side. After a few bends in the trail, turn right at the first junction. Your way straightens out above the former eucalyptus grove to cross Dairy Ravine. High above, the long spine of the park extends for more than 2 miles southeast. Up close, the mountain has a magnificent profusion of poppies and goldfields glowing golden in spring and early summer.
A right turn at the next junction takes you into the trees and thence back to the trailhead. For lunch you can take the footpath through the underpass to the north-side picnic area by the old Monterey cypresses that mark the north entrance to the park.
DAIRY RAVINE LOOP
Climbing higher on the mountain, this trip zigzags up and down the sides of Dairy Ravine past trailside gardens of remarkable beauty.
Distance: 1.75-mile loop
Time: 1 hour
Elevation Change: 325’ gain
In return for the extra elevation gain and extra mileage, this loop offers the delights of coming upon a different rock garden at every turn. Lichen-covered rocks shelter gray-green sedums, their tall flower stalks bearing coral and yellow blossoms.
Starting from the trailhead on the south side of Guadalupe Canyon Parkway, take the left branch of the Eucalyptus Loop Trail (see Saddle Loop Trail) and at the first junction bear left onto the Dairy Ravine Trail. This 0.5-mile-long trail climbs the east side of Dairy Ravine in wide switchbacks to meet the Summit Loop Trail at the head of Dairy Ravine. When you meet the Summit Loop Trail, veer right on it, and see the San Francisco skyline looming in the distance. Below are the old cypress trees in Dairy Ravine. The name and these trees are all that remain of the dairy farm that once operated at the foot of the ravine.
The trail crosses over and makes a switchback above the steep east side of Cable Ravine, then descends quickly through waist-high cream bush, coffee berry, and snowberry to meet the Eucalyptus Loop Trail. Here you take a left turn to return to the south-side parking area.
SUMMIT LOOP TRAIL
This mountaintop climb takes you past the Flower Garden of April Brook Ravine, along the west ridge for its views, and down the steep north face below the summit.
Distance: 3.1-mile loop
Time: 2 hours
Elevation Change: 725’ gain
Although you can complete this trip in less than two hours, you may want to linger longer in spring to enjoy the views and the flowers at every step of the way. From the trailhead on the south side of Guadalupe Canyon Parkway, take the path to the right through the eucalyptus grove.
After crossing the road, you soon come out into dense, waist-high growth—tall cow parsnip with its flat clusters of white blossoms, pink-flowered honeysuckle, and California bee plant with its small, dull red flowers. Along the way you come across the many wet places in the trail where even in summer water is seeping from springs above.
You are soon at the ravine where April Brook flows into willow-bordered Colma Creek. It’s a protected little swale