runfarwhere
Trail · 100K

Sean O'Brien

· starts 5:00 AM
Malibu, CA

WSER Qualifier
The race's site ↗Register ↗Course map ↗

Sean O'Brien is a trail race of 62 miles (100 km) in Malibu, California. The next edition is on Saturday, January 30, 2027, starting at 5:00 AM. The race gives its climbing as 16,246 ft (4,952 m); measured from its course file, it's 14,862 ft (4,530 m). It starts at 550 ft (168 m) above sea level. Its high point is 2,409 ft (734 m). The course finishes where it starts. It's a Western States 100 qualifier. Registration is open to all; registration opened on June 1, 2025. The field is about 250 runners.

There are 42 other upcoming 50-mile and 100K races in California. Sean O'Brien climbs about 261 ft a mile (50 m per km), steeper than 70% of the 119 50-mile and 100K races listed with their climbing.

62miDistance
16,246ftClimbing
250runnersField
63°Flow 46°FTypical race day

The course

62miMeasured distance
12Aid stations
14,862ftMeasured climb
14,865ftDescent
2,409ftHigh point
96ftLow point

Questions about Sean O'Brien

When is Sean O'Brien 2027?

Sean O'Brien 2027 is on Saturday, January 30, 2027, starting at 5:00 AM local time.

Where is Sean O'Brien?

Sean O'Brien is held in Malibu, California.

How long is Sean O'Brien?

Sean O'Brien is 62 miles (100 km).

How much elevation gain does Sean O'Brien have?

Sean O'Brien has 16,246 ft (4,952 m) of elevation gain, as the race states it.

Is Sean O'Brien a Western States qualifier?

Yes. Sean O'Brien is on the Western States 100's list of qualifying races. Check wser.org for the qualifying standard and years.

How do you get into Sean O'Brien?

Sean O'Brien has open registration. Registration opened on June 1, 2025.

What is the weather usually like at Sean O'Brien?

Around Sean O'Brien's date, the day's high is typically about 63°F (17°C) and the low about 46°F (8°C), averaged over recent years.

How many aid stations does Sean O'Brien have?

Sean O'Brien's course has 12 aid stations after the start.

Where can I see the Sean O'Brien elevation profile and aid station cutoffs?

runfarwhere has Sean O'Brien's course file. The outline, distance and climbing are free on its page; the elevation profile, aid stations with cutoffs and the GPX file are part of runfarwhere Premium.

How hilly is Sean O'Brien?

Sean O'Brien climbs about 261 ft a mile (50 m per km), steeper than 70% of the 119 50-mile and 100K races listed with their climbing.

What other 50-mile and 100K races are there in California?

Other upcoming 50-mile and 100K races in California include Anza Borrego Cuyamaca 50 Mile Run (December 5, 2026), Ray Miller 50/50 (December 5, 2026) and Hunter S. Thompson Fear & Loathing (December 6, 2026).

Other races in California

Every race in California

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