At the eastern fringe of the San Francisco Bay Region, Mount Diablo, elevation 3,849 feet, stands alone on the edge of California’s great Central Valley. At this point, the Coast Range consists only of low hills, none high enough to block the view from the upper slopes of the mountain. As a result, the view is spectacular. Many visitors to Mount Diablo head straight for the summit to enjoy the famous view. Summer days are sometimes hazy, and the best viewing is often on the day after a winter storm. Then, you can look to the west, beyond the Golden Gate Bridge, to the Farallon Islands; southeast to the James Lick Observatory on Mount Hamilton at 4,213 feet elevation; south to Mount Loma Prieta in the Santa Cruz Mountains at 3,791 feet elevation; north to Mount Saint Helena in the Coast Range at 4,344 feet, and still farther north to Mount Lassen in the Cascades at 10,466 feet. North and east of Mount Diablo, the San Joaquin and Sacramento Rivers meet to form the twisting waterways of the Delta. To the east beyond California’s great Central Valley, the crest of the Sierra Nevada seems to float in space. With binoculars, you may even be able to pick out Half Dome in Yosemite National Park. Mount Diablo State Park is one of the ecological treasures of the San Francisco Bay Area. Every season in the park has its special qualities. Discover for yourself the mountain's beautiful wildflowers, its extensive trail system, fascinating wildlife and distinctive rock formations. View the stars from its lofty heights, bike ride to its 3,849 foot summit or explore the more remote trails by horseback. The park offers hiking, biking, horseback riding and camping. Dogs must be on a leash under your control at all times. Dogs are not allowed on trails. Dogs must be in a tent, camper or enclosed vehicle during the night. Gates open 8am and close at sunset. Visitors should plan to be in their vehicles by sunset and headed out to avoid being locked in.
Allen T. on Eagle Peak Loop
After doing this loop a few times, my preference is doing the trail in reverse from what is recommended. The ascent up mitchell rock / eagle peak might might be harder, but I prefer it to the rocky steep descent.
Parking is $6 per car, you pay just before entering at a kiosk. Restrooms and a visitor center are available at the trailhead. The parking lot opens at 8 A.M and is accessible until sunset.
Unfortunately, my father and I didn't pick the best day to undertake this trail. There was a race (~25-30 runners) that required us to frequently step off the trail. It was tough to get into a rhythm heading up, which made this trail more difficult. We were able to get to the junction of North Peak/Mount Diablo in a bit over two hours.
The map on AllTrails calls for you to summit Mount Diablo. I decided that North Peak was a better option; Mount Diablo's summit is basically a parking lot, whereas North Peak attracts exponentially less hikers. The only downside is that there are multiple radio towers at the top of North Peak, so you can't fully enjoy the summit. Eagle Peak is the only peak that offers a secluded view of Napa and the bay.
The trail up to Mitchell Rock and Eagle Peak is strenuous, and the remaining trail up to North Peak/Mount Diablo is calf-busting. The route my father and I took (Mitchell-Eagle-Junction-North Peak) had six miles of continuous, unrelenting uphill that will make even the fittest of hikers gasp for breath. The added hindrance of ~90 degree temperatures- and little shade- requires you to drink a lot of water.
Depending on which route you take, about 30% of the trail is on a fire road. The rest of the trail is narrow with terrain, ridges, and occasionally loose rocks. I highly recommend bringing hiking poles to aid you in these areas. Hiking shoes are a must.
Overall, this was a decent outing and I'd do it again. Be wary of the crowds and check for races/marathons ahead of time, especially if you're going on a Saturday. Additionally, check the weather- temperatures climbed as high as 95 degrees Fahrenheit once we got back to the trailhead (1:00 PM.) Have fun!
Great hike in the winter or spring after some good rain. Not usually any water going in summer. Nice to get off the wide roadbeds and on single tracks for the falls, The 1st time I did it was with a friend whose natural hiking speed was faster than mine... It was more like trail running for me! It was good for me!
I've done it several times. Best to do in the spring since there is a lot of sunny open space. In the fall you have a chance to see a few tarantulas. One one of the hikes I was able to see a migration of lady bugs that were close to a foot deep on and around an old stump. Good views and a great workout...
Zoe R. on Mount Diablo Grand Loop Trail
This hike provided a relatively decent hike, but there wasn't a lot of shade for most of the hike. The scenery wasn't breathtaking, perhaps because of the time of year that I went? I'd still recommend trying it out though, if nit just for a day adventure.
Did the trail today (Sep 2016). Its a moderate trail for seasoned folks. For beginners its a hard trail. Partly because sun beats down on you directly if you pick the climb in morning hours. The park opens late (8:00 AM) and that means you can't attempt the climb early in the morning. I think its better to start the trail in afternoon when sun is on the other side of the hills.
Trailhead and other trail information is sketchy at best. We didn’t buy the $6 parking map at the entrance so I am not sure how it would have helped but the map that comes with brochure (given at the gate when you pay $10 entry fees), and that is also available at the website, is of little help in figuring out Trails and trailheads. Many trails and loops adds to the confusion.
Bring water especially if you plan to start late. I drank 1.5 Ltrs during the trip (compare to 0.5 ltr for mission peak). You will have two bathrooms in the trail before you reach the secondary parking lot (read below).
Started at 8:20 and returned at 12:30. We took breaks at top and some other places.
Park at rock city/Live oak campground which is right off the main road leading to summit. This place is ~1.5 miles from the southern entrance. The parking is small and is distributed between different parking lots/places. Plan to arrive early as we saw few people looking for parking when we came down. The summit trail starts at the Southern Gate entrance I think but there is no parking there. Park rangers will tell you to go to the Rock city to start the climb.
You can latch on the trail right at the parking lot or you can walk down to the main road and go a little way up to see two trails on your left. Take the right one. We couldn't locate the trailhead at parking lot and walked along the main road a little way up before we found the trailhead.
Trail crisscross with the main road couple of times and also runs closer to the main road for some part. Trail also merges with fire trails that are dusty.
Keep looking at the summit trail direction in trail signposts at each junction and keep climbing up. You will pass through a sitting area and cross the road before the real climb without shade starts. This part ends when you hit the main road again.
After that you hit flat paved road for sometimes before you climb a little more and reach what we assumed was a fork for upper/lower summit trail (we can be wrong). There is a large water storage facility here and one bathroom.
After this the climb is steep with single file walk. Keep climbing till you hit the road again. The trail doesn’t crosses the road this time but continues to right for slow downhill walk before the steep climb starts again. You end this stretch again at the main road at a scenic lookout point.
At the scenic lookout you are at the road and can see the summit center at top and a large tower far at left. A short steep climb again and you land back at the road again at the secondary parking lot below the summit center. The road to summit forks here with separate way to up and down. Hike a little up the road, cross to get into an area shade from small shrubs and tree. At this point you can continue via the road to the top too. You are very close. The small climb through the shade leads to a large comms tower and immediately after that the trail ends in the main parking lot at the summit center.
Be there at 8:00 if you plan to climb in AM. That way you can avoid too much sun on the way up.
Bring water but 2 ltrs of water one way is too much. You can refill at the top. 1 ltr one way should be good enough.
Wear hiking shoes. Trail is rough at many places with gravel and lose stones. Many places there is too much dirt.
Bring hats and sunscreen to avoid sun exposure