California · 100K · 50 Miler · 50K
Sean O'Brien 100K/50M/50K/26.2/30K
Sean O'Brien 100K/50M/50K/26.2/30K is a 100K, 50 Miler, 50K, 26.2 and 30K event held in Calabasas, California. Its next confirmed date is Saturday, January 30, 2027. About 41 runners take part across all distances.
- Race day
- January 30, 2027
- Location
- Calabasas, CA
- Field size
- ~41 runners
Race details
- Date
- Saturday, January 30, 2027
- Location
- Calabasas, California
- Distances
- 100K, 50 Miler, 50K, 26.2, 30K
- Field size
- About 41 runners
- Course
- 3894 ft gain
- Registration
- ultrasignup.com
- Official website
- khraces.com
Registration, course & weather
- Registration status
- Open
- Entry fee
- Listed fee for the longest distance, $323 (from ultrasignup.com, checked September 27, 2026)
- Start time
- 5:30 AM PST
- Course profile — 50K
- Out-and-back course; Trail surface; 6719 ft gain, 6719 ft loss (estimated from third-party elevation data)
- Course profile — Marathon
- Out-and-back course; Trail surface; 5692 ft gain, 5692 ft loss (estimated from third-party elevation data)
- Course profile — 30K
- Out-and-back course; Trail surface; 3894 ft gain, 3894 ft loss (estimated from third-party elevation data)
- Course profile — 50 Mile
- Out-and-back course; Trail surface; 11492 ft gain, 11492 ft loss (estimated from third-party elevation data)
- Course profile — 100K
- Out-and-back course; Trail surface; 13179 ft gain, 13179 ft loss (estimated from third-party elevation data)
- Typical race-day weather
- about 58°F at the start, 37% humidity, 5 mph wind (based on the 2026 race day, measured near the city center rather than the exact start line; Open-Meteo, checked September 27, 2026)
About the Sean O'Brien 100K/50M/50K/26.2/30K
Sean O'Brien 100K/50M/50K/26.2/30K in Calabasas, CA.
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Guides from the RaceRove blog
- 8 min read How to Choose Your First Marathon A practical checklist for choosing a first marathon based on course, weather, cutoff, travel, field size and support.
- 7 min read How to Find a 5K, 10K, Half Marathon or Marathon Near You A practical way to find running races near you: pick a distance, decide how far you'll travel, read the listing properly and confirm the details before you register.
- 9 min read How to Run a Race in All 50 States How to plan a 50-state running challenge: set your own rules, group states into trips, build a calendar around the seasons, budget for it and keep track of every finish.
- Blog All guides Planning advice for finding, choosing and travelling to races.
Sean O'Brien 100K/50M/50K/26.2/30K: common questions
- When is the Sean O'Brien 100K/50M/50K/26.2/30K?
- The next confirmed date is Saturday, January 30, 2027.
- Where is the Sean O'Brien 100K/50M/50K/26.2/30K held?
- In Calabasas, California.
- What distances does the Sean O'Brien 100K/50M/50K/26.2/30K offer?
- 100K, 50 Miler, 50K, 26.2 and 30K.
- How many people run the Sean O'Brien 100K/50M/50K/26.2/30K?
- About 41 runners across all of its distances. That figure is an estimate of the field size, not an entry cap.
- How do I register for the Sean O'Brien 100K/50M/50K/26.2/30K?
- Registration is handled by the organiser at ultrasignup.com. Entry fees, caps and deadlines are set there.
- Is registration open for the Sean O'Brien 100K/50M/50K/26.2/30K?
- Yes — registration is open. Listed fee for the longest distance, $323 (from ultrasignup.com, checked September 27, 2026).
- What time does the Sean O'Brien 100K/50M/50K/26.2/30K start?
- 5:30 AM PST.
- What is race-day weather usually like at the Sean O'Brien 100K/50M/50K/26.2/30K?
- about 58°F at the start, 37% humidity, 5 mph wind (based on the 2026 race day, measured near the city center rather than the exact start line; Open-Meteo, checked September 27, 2026).
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