Mount Diablo State Park is a 20,000 acre state park in Contra Costa County in the San Francisco Bay Area. The park protects Mount Diablo, an upthrust peak that is only 3,849 feet (1,173 m) tall, yet towers over its surroundings, providing amazing views from its summit that on clear days can stretch as far as Mount Lassen, 181 miles to the north.
In one quick turn on the summit you can see San Francisco, the Central Valley, and when conditions are favorable, the Sierra Nevada. Occasionally capped with a light snow dusting in the winter and packed with countless small rivers and waterfalls in the spring, Mt. Diablo is a nature lover's paradise.
Mount Diablo is sacred to many Native Americans and was considered the point of creation by the Miwok Indians. Today, evidence of Native American presence on the mountain can be seen at Rock City and elsewhere in the park, with grinding holes in the stone showing where the Miwok once smashed acorns and other nuts into powder.
In 1851 the mountain played a vital role in the initial survey of the Western United States when Colonel Leander Ransom chose the south peak of the mountain as his starting point. Subsequent surveys in much of California, Oregon and Nevada were located with respect to this point.
Protection of the mountain began in 1931 when the state acquired land around the peak and created a park. The Civilian Conservation Corps made many improvements to the area during the 1930s, including roads, trails, ranger residences, maintenance buildings, campgrounds and picnic facilities. The CCC also constructed the Summit Visitor Center using stone quarried from the mountain, and visitors today can view shells and other fossils embedded in this natural building material.
On December 8, 1941, the day after the attack on Pearl Harbor, the beacon on Mt. Diablo was turned off to prevent enemy aircraft from using the light to establish their location. On December 7, 1964, there was a ceremony held at the visitor's center on Mt. Diablo which included jets flying overhead and local dignitaries speaking. The purpose was to once again turn on the beacon. On cue, Admiral Chester W. Nimitz, the United States' last surviving fleet admiral, flipped the switch turning on the beacon. Ever since and only once a year, the beacon is on at night on December 7.
In 1971 a push to expand the park and to protect the mountain from development began with the formation of the Save Mount Diablo organization. Since that time the park has increased in size from 6,788 acres to approximately 20,000 acres. In addition, there are more than 80,000 acres surrounding the park that are now protected by a series of preserves, parks, and open spaces stretching from Suisun Bay all the way south to Interstate 580 near Livermore.
As a geologic feature, Mount Diablo is relatively young, having been formed about one million years ago. The mountain lies between converging earthquake faults and was created by uplift that continues today, pushing the mountain higher by 3-5mm each year. The mountain's summit and core are composed of greenstone, an igneous rock that is 90-190 million years old, while the mountain's slopes include large sandstone deposits, formed in ancient seabeds and swamps and filled with deposits of fossils.
Flora and fauna
Commonly seen mammals include coyote, bobcat, black-tailed deer, California ground squirrels, fox squirrels and grey foxes. Mountain lions, peregrine falcon, ringtail cats, badgers, San Joaquin kit fox, roadrunners, tiger salamanders, and burrowing owls are also present but rarely seen. During the winter bald eagles and golden eagles can be found in the park.
Snakes in the area include the Northern Pacific rattlesnake, and visitors should be cautious to avoid startling one, particularly in rocky areas where the snakes often warm themselves. Visitors should also be cautious to avoid poison oak, fleas, ticks and mosquitoes.
Temperatures vary greatly with elevation; snow can often be found at the summit during winter, but is extremely rare at the lowest elevations. The climate data below is from the National Weather Service station at Mount Diablo Junction, which is at an elevation of 2,170 feet, far below the 3,849 foot summit.
|Mount Diablo State Park|
|Climate chart (explanation)|
Park gates open at 8AM and close at sunset. The park is sometimes closed during high-fire danger days in the late summer and when snowfall creates icy roads in late December to mid-January.
The main roads to the park are both called Gate Road, one being called North Gate Road and the other being South Gate Road. These roads connect to the towns in the area.
Fees and permits
Fees vary depending on the park entrance used. The 1 Macedo Ranch Staging Area (Danville) and 2 Mitchell Canyon Staging Area (Clayton) entrances do not provide vehicle access to the summit and charge $6. 3 South Gate Road (Danville) & 4 North Gate Road (Walnut Creek) provide vehicle access to the summit and charge $10.
There is no entry fee charged for those on foot or on bicycle.
Local equestrians and dog owners make extensive use of the numerous fire trails - hikers, watch your step! A popular challenge for cyclists, the ride to the summit is about eight miles of twisty, narrow roads.
- 1 Summit Visitor Center. 10AM-4PM. At the mountain's summit, the visitor center was constructed out of sandstone quarried in the park during the 1930s. Exhibits focus on the cultural and natural history of the park, while a gift shop offers books and other park-related items. There is parking and restrooms available. Outside of the visitor center, an observation area features telescopes to allow enjoyment of the panoramic views.
- 2 Mitchell Canyon Visitor Center. Open on weekends and holidays. The Mitchell Canyon area is noted for its spring wildflowers and is the starting point for a number of trails.
- 3 Rock City. Rock City offers a short, boulder-filled hike among impressive sandstone formations. The most prominent formation is Sentinel Rock, a sandstone monolith with steps carved into it that provides a tremendous view over the surrounding countryside. Other formations include the Wind Caves, Elephant Rock, Lower Rock City, Gibraltar Rock, and the Grotto Picnic area.
- 4 Blackhawk Ranch Quarry. The University of California has been excavating this trove of 9-10 million year old mammal bone fragments since 1926. Specimens found include horses, camels, rhinos, pronghorns, sabre-toothed cats, a fox, and a very large hyena-like dog, although no complete skeletons have been recovered.
The park is filled with trails and fire roads that interconnect, providing a practically infinite number of possible routes. Carry extra water when hiking as it is easy to get lost, and especially on the higher slopes the trails can be strenuous so plan extra time. Many hikers will want to hike to the summit, but be aware that since there is a road to the mountain's top, traffic and crowds can make that trek less rewarding. An alternate option is to hike in the northern part of the park around Mitchell Canyon, which contains fewer people, or to trek to the North Peak, which at 3,557 feet is only slightly less high than the 3,849 foot summit, but since it lacks crowds it is a more peaceful spot to enjoy the view.
- Annual tarantula migration. In September and October thousands of fuzzy male tarantulas venture out of their burrows seeking mates, and can be observed moving across trails and roads; while they may appear intimidating, the spiders are harmless unless provoked. The Mount Diablo Interpretive Association leads guided hikes to see the spiders during their migration, but these hikes are very popular so advance sign-up is required.
- Diablo Challenge. This grueling, 11.2-mile annual bike race starts at the Athenian School at the mountain's base and climbs 3,249 feet up Southgate Road to the summit. The race is held in the autumn and draws around 1,000
masochistscyclists of varying ability levels, with the start staggered into waves of about 150 riders. Prizes are awarded, including a special t-shirt for all men who finish in under 1 hour and all women who finish in under 1 hour and 20 minutes. Proceeds from the event benefit Save Mount Diablo’s land conservation efforts.
There is a gift shop at both the Summit Visitor Center and the Mitchell Canyon Visitor Center. Both sell books, postcards, maps, and other items.
There are no restaurants or snack bars in the park, but many spots along the summit road offer scenic spots for a picnic.
Water is usually available at both visitor centers and at the campgrounds. In summer 2020, mechanical problems and low winter rainfall required the park to ask visitors to bring in all the water they will need during their visit. All campground faucets have been turned off; details are [here]. Hikers should carry plenty of water with them as hiking on the mountain is strenuous, temperatures can rise quickly, and it is easy to get lost and turn a short hike into a grueling slog.
The park offers three family campgrounds that can accommodate tents and RVs up to twenty feet in length. There are also five group camps catering to groups of 20-50 people. Note that the park gates close at sunset, so campers are locked into the park for the night. Campground quiet hours are from 10PM-6AM, and generators may not be used from 8PM-10AM. Campground reservations are recommended but generally only necessary on busy holiday weekends.
- Junction Campground. 6 sites, first-come, first-served only. $30 per night.
- 1 Juniper Campground. 36 sites. Showers are available at no additional charge. $30 per night.
- 2 Live Oak Campground. 22 sites. Showers are available at no additional charge. $30 per night.
Camping is permitted only in designated campgrounds.
Hikers should note that it is easy to get lost on the park's winding trails, so bring extra water and allow plenty of time to return before dark.
Remember that Mt. Diablo is largely wild — there are rattlesnakes, mountain lions, black widow spiders, and many other potentially dangerous animals. Be careful to avoid poison oak. Ticks are present in the park, some of which may carry lyme disease, so exercise appropriate cautions.
- Walnut Creek - Mount Diablo's western neighbor, the downtown Walnut Creek area offers shopping, bars, and restaurants.
- Concord - Located to the northwest of Mount Diablo, Concord is one of the largest cities in the East Bay, offering a variety of shopping and dining options.
- Clayton - Bordering Mount Diablo State Park to the north, Clayton is a bit more rural than other communities and still offers somewhat of a small-town atmosphere.
- Alamo - The town of Alamo borders the park to the southwest.
- Danville - Danville is south of the state park.