Trail Running calendar near Fremont 2025-2026

Diablo Trail Run on Sunday, September 6, 2026 in Clayton CA offers distances from a flat 4 mile to a challenging 50K with sweeping Bay Area views. Marked courses, stocked aid stations and finisher medals welcome all levels.

Autumn trail festival at Lake Chabot Marina in Castro Valley offering 100k, 50 mile and marathon distances through classic East Bay parkland. Expect challenging terrain, a friendly community vibe, and generous finisher swag for all distance..

Run by the Sea returns Sunday, October 4, 2026 at Wilder Ranch State Park in Santa Cruz with 4K, 12K and a half marathon on scenic coastal trails. Now in its 101st year, this charity race supports local youth and trail groups.

Run the 39th Ruth Anderson Memorial Endurance Run on October 10, 2026 in San Francisco. Choose 100 km, 50 miles, or 50 km on a scenic paved loop around Lake Merced with chip timing and certified 50K and 50 mile courses.

Join ZombieRunner Halloween at Hellyer County Park in San Jose on Oct 31 for races from kids dashes to a USATF certified half and marathon. Scenic Coyote Creek trails, festive costumes, shirts and finisher medals make it a fun holiday run.

Enjoy a scenic but hilly trail run at Huddart Park with distances from 3 mile to half marathon, plus a 6 hour challenge and youth dash. Stay for pancakes after the race and choose a virtual option for 5K, 10K or half marathon.