October ultramarathons in California, United States

One-mile hard-packed dirt loop with direction changes every four hours, frequent aid stations, and personal camp support throughout timed ultra options.

Rugged 100-mile route through the San Gabriel Mountains' primitive wilderness, featuring rough terrain and scenic, largely untouched backcountry

214-mile loop race around Mammoth Lakes, spanning the Eastern Sierra with 9,346 m of climbing over five days and a 108-hour cutoff

Three-loop course through Cuyamaca Rancho State Park, summiting Cuyamaca Peak, circling Oakzanita Peak, and running PCT segments with desert views.

Rocky out-and-back 50K course through Bear Valley and Lake Spaulding, steep Signal Peak ascent, panoramic river canyon views, technical terrain

Gold country landscapes, South Fork Yuba River views, forested single-track, fire roads, off-trail sections, and historic town passages

Rugged coastal trails over dramatic cliffs and pristine beaches, with ocean views along the "Mountain of Gold" route

50-mile route from Norco to Huntington Beach, traversing diverse Southern California landscapes with scenic beauty and rugged terrain

Mountain routes near Los Angeles featuring Big Bear Lake views, Sugarloaf Mountain ascents, and descents into Siberia Canyon

Almaden Quicksilver Park start, scenic routes into Sierra Azul Open Space Preserve, Mt. Umunhum summit for marathon and 50K, Bald Mountain peak for 30K

50k trail course through the American River Canyon, scenic Auburn routes, and post-race cider celebration with handcrafted drinks

Looped course around Lake Merced with a challenging route designed for long-distance running

Brutally demanding canyon ultra near Foresthill, with huge elevation change, rough terrain, off-trail sections, and a remote backcountry feel.

Varied Skyline Park trails with multiple 4.1-mile loops, 815 feet of elevation gain per lap, fire roads and singletrack, run at own pace

Time-based ultrarun in Napa's Skyline Wilderness Park, 4.16-mile trail loop with 815 feet of gain per lap through rolling hills and historic landscapes

Timed trail run at O'Neill Regional Park with scenic canyon loops, dense oak and sycamore groves, cactus-dotted hillsides, and 500 feet of elevation gain per 2.

Rugged terrain and remote trails in the Santa Ana Mountains, 50M and 50K routes on single track and forest roads with challenging elevation and striking scenery

Rugged Cleveland National Forest and Santa Ana Mountains routes with significant elevation gain, technical terrain, and panoramic views.

Looped golf course circuit with rolling fairways, cart paths and lakeside stretches, framed by Sierra foothills and Central Valley orchards.

Point-to-point route on the Fernley and Lassen railroad line, descending through Susan River Canyon and crossing historic wooden bridges in Lassen National