Mount Umunhum

"The Cube", a 5-story concrete former Cold War radar installation on Mt Um's summit
Extensive views of San Jose and all of the most prominent summits of the Bay Area on a clear day -- Mt Tamalpais, Mt Diablo, and Mt Hamilton

Routes

Mount Umunhum Trail

6 summits • 8.5 mi • 1,160 ft gain • 2 hr 9 min • Class 1

Mount Umunhum 10.4 mi route

1 summit • 10.4 mi • 1,075 ft gain • 6 hr 22 min

Mount Umunhum 9.4 mi route

1 summit • 9.4 mi • 1,064 ft gain • 3 hr 49 min

Latest summits

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"Parked at the Bald Mountain parking lot. Got there about 10ish. Only a few other cars in the lot with one group already returning. Quickly packed up and hit the trail head across the road. Started with no wind, mostly clear skies and about 49 degrees. Had the trail to myself to start but was met by a group of about seven deer that were grazing on the trail. They had no fear of me and when I got too close they would simple trot a few feet away and continue grazing. After a bit they left the trail and melted back into the trees. The trail is great. A gentle grade the whole way, did not use my trekking poles at all. Total worth making the very short trip off the main trail to the Guadalupe Creek overlook. Amazing views at several points along the trail. Only saw a few others on the trail on the way up. Unfortunately one group was very loud, no music, just talking. I do not go out on the trails to clearly hear others conversations from several hundred yards away. This would also be an issue on the return trip as the trail got busy. The summit was amazing with 360 views. Wind at the summit was about 20-25mph. Not crowded but I would imagine that this area is packed on weekends. Returned..." — Mtstalker • Jan 3, 2020

"Landed at SJC at 9 and was on the trail by 10. The Open Space space folks did a great job restoring this area and building trails and facilities at the summit. Really enjoyable quick hike with a lot of history." — edg • Jan 19, 2019

"Midpeninsula Regional Open Space District Sierra Azul Open Space Preserve Mt. Umunhum Trail 10.43 Miles Ascent 1,075 ft (-1,075) 12 Geocache(s) 1 BenchMark 1 WarkMark 2 Peaks 6:22 Total Time" — jminkema • Mar 11, 2018

"Nice trail - easy to hike. The peak is immaculate, seriously clean (felt bad for dropping chip crumbs). The trail to the radar tower is closed, but you can still get to the peak on the road and up a few flights of stairs. " — colleenmarie512 • Dec 2, 2017

"Great fall trailrunning up the brand new Mt Umunhum Trail. Started at the Bald Mtn parking lot at ~2300ft with the intention of just hiking up. But when I saw the slight grade of this new, highly buffed trail I couldn't control my legs and started out in a run. The grade never really increased and I just chugged along up the looooong, gradual switchbacks. ~1200 ft vert in 4 miles at a constant low grade makes for about the easiest running ascent I've ever experienced. The trail builders clearly designed it to be an achievable summit trail for a large swath of visitors. Despite not being a fan of summits with roads to the top ("This car climbed Mt. Washington"-- BOOO), I do think the way they arced the Mt Um trail below the road and onto the summit plateau is well done and really scenic. And the summit plateau is really thought out and interesting to explore; can't imagine what a mess it must've been up here before the 8 year, $25 million cleanup effort. Glad they decided to keep the cube... definitely gives what would otherwise be a broad fairly non-descript summit a unique and historical feel. " — scott • Oct 3, 2017

"Knowing that I'm leaving the area soon, my friend at the Umunhum Conservancy invited me along on a supporter's visit. So glad to legally get this summit. The plans for the top look nice and there will be a 4.5 mile multi use trail to the summit from Bald Mountain parking for those don't think driving to the top is a true summit. :D" — calipidder • May 28, 2016