Trail Running calendar near Fairfield 2026-2027

A fall trail event in Auburn featuring three distances along the American River Canyon, aid stations on the longer courses, live music, and complimentary cider pours at Ponderosa Cider Co on October 10, 2026.

Test your endurance at Lake Merced in San Francisco with a scenic 4.5 mile loop course. Choose between a standard run or tackle ultra marathon distances including the 50K and 50 mile events.

Granite Head Trails & Ales Trail Races feature 6.6-mile and 11.2-mile courses. Runners get a tech T-shirt and can enjoy post-race fajitas and a beer. The event is the final race in a local trail running series.

A trail race at Almaden Quicksilver County Park with distances from 5K to 50K. Courses are out-and-back, marked with colored ribbons, include aid stations and toilets, and the longer races reach Bald Mountain and Mt. Umunhum.

A 12.4 mile loop up to the Mount Diablo summit and back in Clayton, California, featuring about 4,000 feet of ascent and descent and a 5 hour cutoff. Entry includes a shuttle, raffle entry, and a unique finisher item.

Trail races from 5K to 35K around Briones Reservoir near Orinda, CA, featuring mixed single-track and fireroad terrain, chip timing, cupless aid stations, and a 300-runner capacity.

Insomnia is a night trail race in the Sierra Nevada foothills offering 35K, 14K and 5K options. Courses are marked with reflective ribbons and headlamps are required; the 35K has a 5 hour 30 minute overall cutoff.

Trail running in Cool, California with 5k, 10k and half marathon options on Sierra Foothills trails. Proceeds support Georgetown Divide Ready by 21 and a Camp Taylor scholarship; family packages, childcare, and a post-race breakfast are inc..

A multi-distance trail event at Lake Sonoma on October 17-18, 2026, offering 100 mile, 50 mile, marathon and relay options. Courses use extensive singletrack with lake views, aid stations, crew access, and free on-site camping for participa..

Run through the historic site of the 1848 gold discovery in California. This event features multiple trail distances from a 5K to a Half Marathon on scenic singletrack paths along the American River.

A trail running event at Mount Diablo in Walnut Creek on October 17, 2026 offering 30K, Half Marathon, 10K and 5K courses on hilly trails where mud and creek crossings are possible.

A 5k cross country race run in two loops around Willow Hill Reservoir next to Folsom High School, part of the Pacific Association USATF Cross Country Grand Prix, with a $75 bonus for breaking an age group record.

A themed charity run and community festival on October 18, 2026 in Downtown Roseville, CA, supporting the bleeding disorders community. The day includes a timed 5K, a one mile walk, festival food, carnival games, and a remembrance ceremony.

A Last Person Standing format at Beals Point, Granite Bay where runners complete a 4.16 mile loop each hour until one remains. A 12 hour Mini version is available, with start area aid and wood awards plus a quarter zip for entrants.

A repeating 4.16-mile trail loop event at Beals Point where runners start a new lap each hour until one remains; a Mini version ends after 12 hours. Aid is only at the start/finish and personal aid areas are encouraged.

A trail race at Acorn Creek Trailhead near Pilot Hill offering a 10K lap and a two-lap half marathon on singletrack with creek crossings and scenic overlooks. The event raises funds for the American River Conservancy and supports local trai..

Trail marathon, half marathon, 10K and 5K at Bothe-Napa Valley State Park on October 24, 2026. The single track course features hills, streams and rocks, is marked with orange ribbon, has limited entry and specific cutoff times.

Trail races through Redwood Regional Park in Oakland on October 24, 2026 offering 10K, half marathon, and 35K courses. Technical trails, substantial elevation, chip timing, cupless aid stations, and limited field size.

A Halloween-themed running event at Hellyer County Park with 5K, 10K, half and full marathon distances, youth divisions, a free kids' dash, a costume contest, certified half and full courses, aid stations every 2-4 miles, and cupless hydrat..

Trail races in Almaden Quicksilver Park from 5K to 50K over hilly dirt roads and single-track, with two staffed aid stations, drop-bag service for longer distances, and a finisher medal for all participants.