Cuyamaca 100K Endurance Run

Cuyamaca 100K Endurance Run takes place in Julian, California, on October 3, 2026. The race is a single 100K (62 miles) trail ultra in the Cuyamaca area east of San Diego, with a 5:30 AM start that puts the first miles in the dark and leaves plenty of daylight for the bulk of the course.

A 100K is a meaningful step up from a 50-miler in both time and fueling demands, and it is a common stepping stone for runners aiming at a 100-mile race the following year. You should arrive with at least one 50K finish and ideally a 50-mile race under your belt. The training block that works for most runners is 20 weeks long, with back-to-back long runs on weekends, regular climbing sessions and at least one 30-to-35-mile day to test your fueling plan. Southern California in early October can be warm in the exposed sections, so practice drinking on a schedule and consider electrolytes. Sort out drop bags and a headlamp for the pre-dawn start, and expect to spend 12 to 18 hours out there depending on your fitness.