South Mountain - Mormon Trail to Fat Man's Pass

About South Mountain - Mormon Trail to Fat Man's Pass

South Mountain Park is the largest municipal park in the United States, spanning over 16,000 acres along the southern edge of Phoenix. The Mormon Trail to Fat Man's Pass is one of the most enjoyable and interesting routes in the park, combining a moderate workout with a fun geological feature that makes it a favorite for both locals and visitors. The trail begins at the 24th Street trailhead, which has a dirt parking area that can accommodate a decent number of vehicles.

From here, you head south on the Mormon Trail, which starts with a gentle incline through rocky desert terrain. The landscape here is drier and more rugged than what you find in the northern Phoenix mountains. Creosote, brittlebush, and jumping cholla are the dominant plants, and the exposed dark volcanic rock gives the hillsides a stark, almost lunar quality.

Within the first half mile, observant hikers will notice petroglyphs on some of the darker rock surfaces. These ancient rock carvings were created by the Hohokam people who inhabited this area over a thousand years ago. Please look but do not touch them, as oils from skin can damage these irreplaceable cultural artifacts.

The trail climbs steadily through a series of rocky switchbacks that offer increasingly impressive views of the Phoenix skyline to the north. The contrast between the raw desert landscape and the modern city sprawling below is striking. On clear days, Camelback Mountain and Piestewa Peak are clearly visible across the Valley.

The main attraction is Fat Man's Pass, a narrow cleft in the rock that you squeeze through to continue on the trail. The gap is roughly 18 inches wide at its tightest point, and taller or broader hikers will need to turn sideways and duck slightly. It is a fun challenge that gives the hike a memorable focal point.

There is an alternate path around it for anyone who does not want to attempt the squeeze. Beyond Fat Man's Pass, you can continue along the ridgeline for additional views or turn around for the return trip. The descent back to the trailhead is straightforward but watch your footing on the loose volcanic rock, which can be slippery.

Practical notes: this trail is dog-friendly, and you will see plenty of dogs on leashes here on weekends. Bring water for yourself and your pet. There is no shade to speak of, and the dark rock radiates heat intensely in warmer months.

The 24th Street entrance has no fee, unlike the Summit Road entrance to the park. Parking can get competitive on weekend mornings in peak season, so arriving before 8 AM is wise. Mountain bikers also use some of the connecting trails in this area, so stay alert at junctions.

This is an excellent moderate hike with personality and history that sets it apart from the typical desert trail.

Best Time to Hike

Best Season: October through April

For the most comfortable experience on South Mountain - Mormon Trail to Fat Man's Pass, plan your hike during the recommended season. In the warmer months, start early in the morning to avoid peak heat, especially on exposed desert trails. Always check current weather conditions and trail status before heading out.