Region
Highlights
- "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
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
8 summits • 8.5 mi • 1,160 ft gain • 2 hr 12 min • Class 1
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
1 summit • 17.0 mi • 2,585 ft gain • 5 hr 47 min
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
1 summit • 10.3 mi • 3,166 ft gain • 4 hr 21 min
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
1 summit • 10.4 mi • 1,075 ft gain • 6 hr 22 min
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
1 summit • 9.4 mi • 1,064 ft gain • 3 hr 49 min
/-121.89888420105,37.1602052084901,11,0.00,0.00/320x240@2x?access_token=pk.eyJ1IjoicGVha2VyeSIsImEiOiJjampra3Z0bnAxeTVnM3FteHlybHY3b2p1In0.7a5dEa5-995VUv8ceHHNmw)
1 summit • 9.8 mi • 968 ft gain • 3 hr 4 min
Latest summits

"Despite the recent rain and high winds in the Bay Area, the trail is in very good condition: no downed trees, no mudslides, and only 2-3 spots on the Barlow Road with standing mud/water (which were easily avoided)." — michaelwin • Jan 12, 2023

"This hike goes for 7 miles. We saw some car wrecks, some bridges, and crossed a junction. The trail passed through a forest for most of the hike. We went to Guadalupe Creek Overlook as well. There is no benchmark on the summit" — lc4441 • Sep 7, 2022
"An easy twofer from Bald mountain PA. Mount U first on a nice wide trail with plenty of switchbacks. Unfortunately the final stretch of trail, access road, building and true summit were closed do to work being done on the building. Back to the PA and onto an easy stroll up to the little knob of Bald. Great view that was reduced a bit with the smog/haze from the toasty temps." — Nimblefoot • Jul 30, 2021

"Hot day in San Jose in the 90s. Dropped a car at the Umunhum summit around 11am, and shuttled the four of us down to Jacques parking lot. Lot was full, but we were able to park on a nearby street.
Headed up the trail from there. Mixed shade and full sun exposure areas. Was much less hot up there compared to on the valley floor, and managed to get by without a sunburn.
Took a detour for the Bald Mountain trail which was mostly flat, only about 2 miles and overall pretty relaxing.
Apart from the lack of any breaks, our pace was fairly leisurely. We passed quite a few people (maybe 50 total). About half wearing masks for COVID. Views were better than expected. Great hike.
We reached the Umunhum summit 4.5 hours after starting. 10.8 miles total, 2600ft elevation gain." — HolyBejeesus • May 24, 2020

"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