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Sean O'Brien 100/50M/50k/26.2/30k

location_on

Calabasas, California, United States

calendar_today 31 Jan, 2026

directions_run Running

sell $95.00 – $190.00

About the Event

Tackle the iconic and demanding trails of the Santa Monica Mountains at the Sean O'Brien Ultra-Marathons, a premier event set for Saturday, January 31, 2026 in Malibu Creek State Park. This legendary race offers a spectrum of distances from a 30k to a grueling 100k, with the 50 Mile serving as a Sterling Silver Ticket race for the Angeles Crest 100 and the 100k as a coveted qualifier for the Western States Endurance Run.

Runners will navigate a challenging, cupless course through some of Southern California's most breathtaking and rugged terrain, requiring self-sufficiency and resilience. With staggered early morning start times, the event captures the serene beauty of the coastal range, testing both physical endurance and mental fortitude across its world-class routes.

Directed by renowned ultra-runner Keira Henninger, this race is a cornerstone of the winter ultrarunning calendar, attracting elite athletes and dedicated trail enthusiasts alike. It's a true test on historic trails where every finish represents a significant achievement in the sport.

Races Offered

100K

Jan 31, 2026

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Distance — 100K

terrain

Type — Running

timer

05:30

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$190.00

50 Miler

Jan 31, 2026

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Distance — 80.5K

terrain

Type — Running

timer

06:00

sell

$150.00

30K

Jan 31, 2026

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Distance — 30K

terrain

Type — Running

timer

07:00

sell

$95.00

50K

Jan 31, 2026

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Distance — 50K

terrain

Type — Running

timer

07:00

sell

$115.00

Marathon

Jan 31, 2026

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Distance — 26.2K

terrain

Type — Running

timer

07:00

sell

$105.00

Weather Overview

These values represent the 3-year monthly averages for January in Calabasas.

Temp (°C)

Feels Like (°C)

thermostat 7.3° / 17.1°

wb_sunny 3.9° / 14.1°

Wind (km/h)

Humidity (%)

air 9.3 /

water_drop 60.4%

Temp (°C)

Feels Like (°C)

Wind (km/h)

Humidity (%)

thermostat 7.3° / 17.1°

wb_sunny 3.9° / 14.1°

air 9.3 km/h

water_drop 60.4%

About Calabasas

Learn more about the host city, Calabasas.

Calabasas is a suburban community at the southwestern corner of the San Fernando Valley of Los Angeles County, sitting in the foothills of the Santa Monica Mountains to the south.