Sunday, September 10, 2023 • Clayton, CA • Course Map
Standing at 3,849 feet above sea level, Mount Diablo offers one of the toughest challenges of any trail run among the many parks and mountain peaks here in the San Francisco Bay region, a steep and relentless uphill run from the start to the peak of the mountain that also offers some of the most spectacular views from the eastern edge of the Bay Area, looking out onto Northern California’s Central Valley.
The Diablo Trail races feature five race distances, the shortest of which (the four-mile trail run) offers a relatively flat course through the section of Mount Diablo State Park known as Mitchell Canyon.
The other four races — including the full marathon, half marathon, 50K and 10-mile trail runs — feature more challenging routes, with the half marathon climbing more than 3,400 feet in elevation between the starting line at the mid-way point of the race, near the peak of Mount Diablo.
Runners start the race at Mitchell Creek Park just off Mitchell Canyon Road, near the northern entrance to Mount Diablo State Park.
From there, they follow a combination of fire roads and single-track trails from the start all the way south and east toward the summit, along the Mitchell Canyon Road for the first five and a half miles or so, followed by a stretch along the Juniper Trail that leads to the mountain summit.
Once runners reach the top, they turn around and head back down the mountain along the route they’ve just run, all the way back to Mitchell Canyon Park for the race finish.
While organizers will have water and aid stations out on the course, runners are encouraged to bring along water bottles with them during the race to ensure they stay properly hydrated out in the backcountry wilderness of this nearly 20,000-acre park.
Along the course, runners can expect to see a wide variety of plant life and perhaps even wildlife, thanks to the wide range in elevation within the park, which ranges from 300 feet to nearly 4,000 feet above sea level.
Mostly populated with central California oak trees, grasslands and chapparal, the trails and roads are also made up of riparian woodlands at the lower elevations, where streams and creeks run throughout most of the year.
Race Weather & Climate
Located just north of Mount Diablo State Park in Northern California, just over 30 miles northeast of San Francisco, Clayton typically sees warm and very dry weather in September, which has brought record temperatures here as low as 42ºF (in 1970) and as high as 107ºF (in 1998).
On race day (Sep. 10), the average low is 51ºF and the average high is 87ºF.
- 2022 Results
- 2021 Diablo Trail Run Half Marathon Results
- 2020 Diablo Trail Run Half Marathon Results (Virtual)
- 2019 Diablo Trail Run Half Marathon Results
- 2018 Diablo Trail Run Half Marathon Results
- 2017 Diablo Trail Run Half Marathon Results
- 2016 Diablo Trail Run Half Marathon Results
- 2015 Diablo Trail Run Half Marathon Results
- 2014 Diablo Trail Run Half Marathon Results
- 2013 Diablo Trail Run Half Marathon Results
- 2012 Diablo Trail Run Half Marathon Results
- 2011 Diablo Trail Run Half Marathon Results
- 2010 Diablo Trail Run Half Marathon Results
- $55 and up – half marathon
- $40 and up – 4-mile
- $45 and up – 10-mile
- $65 and up – full marathon
- $75 and up – 50K
To reserve your spot in any of the races at the 2023 running of Clayton’s Diablo Trail Runs, register online at RunSignUp here.
Official Race Website
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