Trail Guide: Mount Diablo via Regency Gate (10-12mi / 3,500′)

Trail Guides

Rising to just 3,849′, Mount Diablo may seem, well, short when compared to the sierra mountains just a few hours to the east. Yet driving into the Bay Area from those very same mountains, the double peak outline is often visible a hundred miles out while the climb from the base to the top rivals the elevation gain of all but the most aggressive Tahoe day hikes. Diablo may not be a snowcapped mountain (at least not these days) but it is an impressive adventure just the same.

There are plenty of trails to to the top of Diablo starting from all sides of the mountain and may routes even from there, each with their own experience to offer. With COVID-19 and staying local, I’ve been working my way through many of them this year and this post covers the pros, cons, and highlights of the routes from Regency Gate up including:

  • Back Creek Trail via Bald Ridge, North Peak Trail
  • Donner Canyon via Meridian Ridge Prospector’s Gap Road, North Peak Trail
  • Donner Canyon via Middle Trail, Prospector’s Gap Road, North Peak Trail
  • Eagle Peak Trail via Bald Ridge Trail, North Peak Trail

COVID-19 Note: Mount Diablo State Park is open for hiking as of when this was posted. However , parking lots, most restrooms and other facilities are closed for now. Park guidance is to stay local, walk or bike to the park. This post talks about the general trails but be sure to stay updated on the current park conditions.

Getting to the Trailhead

This trail route starts from Clayton at the end of, you guessed it, Regency Drive. There’s no parking lot though there is street parking available along the road. On weekends and holidays (and all the time during COVID-19 / shelter in place), street parking is restricted with a dozen or so spots at the end of the road and more a quarter mile back.

Please be sure to respect the local residents by parking away from driveways, following all posted parking signs (they are well enforced) and keeping the noise down as you walk by people’s houses.

Facilities, Lodging & Things Around the Trail

There are no facilities at the trailhead or on this trail until you’re nearly at the summit. Be sure to bring plenty of water and be ready for wilderness restroom use following Leave No Trace.

Mount Diablo Summit Visitor Center
Mount Diablo Summit Visitor Center

For food, water or other supplies, there is a CVS on Clayton Road which I believe is the closest store. 7-11 and other gas stations and markets can also be found a few miles back towards Clayton and Concord.

Hiking to the Summit: Trail Options

Even from this one trailhead, there are a host of fairly direct options to decide between to get to the top of Mount Diablo though all end with the same final stretch up North Peak trail. Following your topographic (trail) map, you can pick between routes to shorten the distance or ease up the incline, widen the trail to avoid poison oak and crowds, narrow in for more shade, and just to change the view.

Park Map

Back Creek Trail via Bald Ridge is the main route to the top listed on AllTrails so I suspect also the most busy on a weekend but for good reason. The trail starts off with the same fireroad approach as the other major routes but quickly takes a turn into the shade of the forest which it stays under much of the way to the North Peak trail junction.

The route passes by a few small streams (seasonal only) and has some really nice forest views early on before it starts to climb more aggressively up towards Bald Ridge. Bald Ridge starts off with some nice, rocky terrain (no significant climbs but a fun change up in the view) before returning to a forested hike.

The ridge also drops elevation briefly meaning you’ll have to climb up a couple hundred extra feet r/t. The longest of the 3 main routes I’ve taken at around 12+ miles r/t, things are rarely flat but the inclines are less dramatic. However, the trail is a bit longer so more time walking and it’s rather narrow making crowds harder to navigate. The tree cover is appealing for shade but with it comes a decent amount of poison oak so be careful of where you walk.

My take: My favorite route to go back down (on a non-crowded day) for its slightly more gentle climb and plentiful shade.

Donner Canyon via Meridian Ridge Prospector’s Gap Road lets you hike all the way to North Peak trail along fire-roads offering plenty of space for a small group hiking together and while passing by other hikers. This comes at the expense of any and all shade but also the perk of removing just about all poison oak risk. All said, this route is a bit over 11 miles r/t.

While the fire-roads don’t offer the forest views, Donner Canyon trail is a downright pretty view in late winter and spring as you head off on the rather flat first leg of the trail passing by rolling hills and a few clusters of large trees. As you near Meridian Ridge Trail, the incline picks up sharply and the trail becomes a solid hike making up for the slow start.

The wide open road means you can frequently catch a view of Diablo’s summit up ahead and off to the east behind you (aka an excuse for a break). It’s not the most exciting of trails but it’s not bad all things said. In summer, the lose soil from the well worn road really dries out and it’s easy to lose your footing on some of the steeper sections.

My take: The best option if you want to avoid crowds or hike with a few others.

Donner Canyon via Middle Trail combines a bit of the first two route’s experiences while also cutting out another mile at 10 and change r/t. It’s steep, sometimes shaded and has some nice views across to North Peak and the ridge to the south.

Things start on the same Donner Canyon fire-road with the same views but just as you pass the junction at Meridian Ridge, Middle Trail splits off. While a single track trail like Back Creek, Middle Trail seems to be less frequented though it’s also not nearly as shaded. This is where the views really change up as you get a fairly clear look out across the valley to your south.

Middle trail rejoins the previous route 0.7 miles before Prospector’s Gap and basically serves as a shortcut skipping some of the wider turns the fire-road has to make.

My take: The best route up for a solid workout without always being on a freaking fire-road.

Eagle Peak Trail via Bald Ridge Trail is not really what I’d call direct but it’s not a ton longer so I’ve included it as an alternative adding another view and for a bigger climb. The extra mileage is off-set by the 360 perspective from Eagle Peak which is one of my favorite spots on the east side of Diablo. Of course, you may not be so happy with me after the steep descent down from the peak, losing 200′ which you promptly must regain to reach the Bald Ridge Trail junction.

You can route the return via Back Creek to avoid re-doing that extra climb or connect in with Mitchel Canyon if you’re starting / shuttling from the larger parking lot.

North Peak Trail is the shared ending from all these routes as you meet up at Prospector’s Gap (also where the North Peak trail breaks off if you want to do that instead or both for a bigger day).

The single track trail cuts across the side of the mountain as it winds up the last ~900′. With basically no cover, this section of the trail is really exposed and gets cold on a foggy day, super hot on a summer afternoon but also gives you some great views along the way. In spring and early summer, you’ll find plenty of wildflowers blooming along the slopes here but will also notice the impact of past wildfires and the remains of scorched trees.

The final 400′ of climbing is done alongside the road to the summit and intersects it directly a few times (no cheating and getting a ride up!). Be sure to cross the road and re-gain the trail around the summit to avoid getting hit by a car or flying bike. If you need a restroom, I suggest the ones by the parking lot to your left at the second road junction, you can also refill water and stretch out for a bit on the picnic tables there.

As you reach the summit, you’re likely to find plenty of people given that well, you can drive to it. The visitor center has a few snack options and there is water (good, cold water) and restrooms, to use after taking in the impressive and far reaching views all around the Bay.

Return down the way you came or connect a different route to change things up and make a loop.

Hiking to the Summit: What to Bring with You

Diablo may be just a few miles from home but with miles of trail, it gets surprisingly remote real quick with very little in the way of facilities from this side of the mountain. Before you head out for the day, be sure to prepare for what’s ahead, packing up a solid day kit, checking the latest park conditions and keeping an eye on the weather.

Be sure to bring the 10 essentials and I’ll especially emphasize having a trail map to navigate the different forks in the trails (cell signal is generally good around Diablo but don’t rely on having it or enough battery power), plenty of water & food, extra layers, sunscreen for an exposed day, a headlamp if you end up out later than planned and of course, a nice summit treat (or a few bucks to buy one if the Summit visitor center will be open during your hike).

All these routes are rather exposed to the elements and conditions range from frigid if not icy in winter or just on a cold Bay Area morning to dangerously hot in summer. Being prepared keeps you safe and also makes for a much more enjoyable day.

Quick facts about the trail:

  • Route: Out and Back or Loop
  • Official Rating: Difficult
  • Start point: Regency Road, Clayton CA
  • Distance: ~10-12 miles r/t
  • Duration: 4-6 hours
  • Elevation Gain: 3,500′ (or more)
  • Facilities: None until the summit
  • Water: None until the summit
  • Crowds: Moderate to Heavy
  • Cell coverage: Good
  • Permits & Fees: None

Additional Info: