Cerro San Luis Loop
Quick Facts:
- Time: 3 hours
- Distance: 5-mile loop
- Elevation: 1280'
- Difficulty: Moderate with some steep sections
- Terrain: Mix of single track trail and wide jeep road
- Shade: About 1/3 shaded
- Dogs: Allowed on leash, watch for bikes
- Parking: Fernando Lane (end of residential area)
- Also known as: Mt. Madonna
Learn about elevation profiles
Trail Overview
Our regular route takes the M Trail past the eponymous the "M" marker, which is visible from Highway 101. From there it ambles downhill to the historic lemon grove, and up the aptly-named Rock Garden trail. The summit includes a platform for ceremonies and a sturdy fixture for annual Christmas tree lights. Mostly exposed to the elements, the downward walk follows a wide jeep trail that's easy to navigate.
Key Route Segments
A strong incline gets steeper until the second overlook bench. This section sometimes spreads out hiking groups, but we often stop at junctions for everyone to catch their breath and remove jackets.
The M Trail ascends further, but not as steeply, reaching its highest point at the eponymous “M” that’s visible from below.
The trail descends through oak trees (and poison oak) along switchbacks that include raised platforms over the rough spots. This side is pleasant in summer and provides a chance for recovery and conversation as you walk. The trail ends at a grove of planted lemon threes, then doubles back around the northeast side of CSL. Bishop Peak is visible ahead, and Cal Poly to the right.
Like a slice of Bishop Peak, the Rock Garden trail requires some high knees over uneven ground. The trail varies in width, so watch out for hikers and serious mountain bikers. Two scenic overlooks make good places to pause.
You’ll reach the summit after a final switchback along the top ridge. There’s a wide, flat space with plenty of room for hikers, dogs, and bikes. Optionally scramble to the very summit where they assemble an annual Christmas tree of lights, or hang out at the wooden platform. Allow 15–20 minutes for rest, snacks, and snapshots in all directions.
The descent follows a jeep road along the west and south sides of CSL. Leaving from the platform, take a slight right turn (north) to the jeep road, which curves down the north, west, and then south sides of the peak. This is a wide track, exposed to the elements and often windy since it faces the Los Osos Valley. Expect hikers to get spread out here.
Weather and Timing
The trail has little shade beyond the eastern forest section, making summer hikes hot in the afternoon. In 2024 the city installed a sign directing hikers along the correct trail back to the parking area at Fernando Lane, which helps with navigation especially as light fades.
Although the preserve closes after dark, the city hands out a limited number of hike permits in November–March for after hours hikes.
Technical Challenges
- Slippery sections after rain
- Rock Garden trail requires attention to footing
- Limited shade on western portions
- Can be windy near summit
Photos by Joe Gremillion