Sean O'Brien 100K 2027
The forecast arrives five days before the start.
Here you'll find the elevation profile, an estimated finish time based on your UTMB Index and details of the 10 aid stations to plan your nutrition and hydration segment by segment.
What's your time based on your UTMB?
Times estimated by the RAVIT model, learned from real ultra-trail finish times. Enter your UTMB Index (utmb.world) to get a personalized estimate.
Cut-off times and crew - Sean O'Brien 100K · 2027
Data from the official race rules, checked for every edition. The race rules prevail. Positions are interpolated along the GPX track and are a guide, not official course marking.
What you'll find at each aid station
| Product | Corral Canyon Aid #1, #2 and #3km 11.7 | Kanan Aid #1 and #2km 21.7 | Zuma Edison Ridge Aid #1 and #2 (miles 19.2 & 31.3)km 25.9 | Bonsall Aid #1 and #2km 35.9 | Bonsall Aid #1 and #2km 41.5 | Zuma Edison Ridge Aid #1 and #2 (miles 19.2 & 31.3)km 51.4 | Kanan Aid #1 and #2km 55.6 | Corral Canyon Aid #1, #2 and #3km 65.6 | 100k Turnaround - Bulldog Aidkm 76.5 | Corral Canyon Aid #1, #2 and #3km 87.2 |
|---|---|---|---|---|---|---|---|---|---|---|
| Water | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ |
| Brand products | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ | ✕ |
Elevation profile
The course and its aid stations
Sean O'Brien 100K: times, aid-station stops and fuelling needs by UTMB® Index
Between a UTMB® Index of 500 and 800, the estimated finish time on this race runs from 18h35 to 11h01, and the aid-station stop budget from 1h03 to 0h21. The longer the race, the more stops weigh: this is time you should plan to spend standing still, not only running.
Below a UTMB® Index of roughly 565, the overall cut-off of 17h00 is no longer reachable at the estimated pace.
| UTMB® Index | Estimated time | Of which stops | Night hours | Carbs | Fluid | Sodium | Cut-off margin |
|---|---|---|---|---|---|---|---|
| 500 | 18h35 | 1h03 | 4.6 | 1,115 g | 13 L | 9,289 mg | −1h35 |
| 550 | 17h12 | 0h52 | 3.2 | 1,032 g | 12 L | 8,604 mg | −0h12 |
| 600 | 15h17 | 0h41 | 1.5 | 917 g | 10.7 L | 7,642 mg | +1h43 |
| 650 | 13h41 | 0h33 | 1.5 | 821 g | 9.6 L | 6,838 mg | +3h19 |
| 700 | 12h39 | 0h28 | 1.5 | 759 g | 8.9 L | 6,328 mg | +4h21 |
| 750 | 11h56 | 0h24 | 1.5 | 716 g | 8.4 L | 5,965 mg | +5h04 |
| 800 | 11h01 | 0h21 | 1.5 | 661 g | 7.7 L | 5,509 mg | +5h59 |
Figures based on 60 g of carbohydrate, 700 mL of fluid and 500 mg of sodium per hour, "average" preparation and mild conditions (15–25 °C). Above 25 °C, count on roughly 900 mL/h and 700 mg/h. Carbohydrate intake is trained: 60 g/h is a floor, 90 g/h assumes a glucose-fructose blend and a gut used to it.
Other trails worth preparing for
- Ghost Train119 km · 626 m D+ · October 17, 2026
- Wild Duluth 100k97 km · 3,157 m D+ · October 17, 2026
- Rogue Gorge 5081 km · 862 m D+ · October 17, 2026
- Man against horse77 km · 1,910 m D+ · October 17, 2026
- Horseshoe Bend 50 Mile81 km · 1,108 m D+ · October 17, 2026
- Lake Sonoma 5081 km · 2,922 m D+ · October 17, 2026
- Pocatello Round114 km · 5,412 m D+ · October 17, 2026
- Firewater 100K97 km · 1,314 m D+ · October 24, 2026
- Island View 100154 km · 6,966 m D+ · October 24, 2026
Sources and method
- Time projection — les temps par cote sont repris des passages réels des coureurs de chaque tranche sur les éditions précédentes de cette course, arrêts aux ravitaillements compris. Aucune formule n'intervient tant que ces résultats existent.
- Trail nutrition — hourly targets for carbohydrate, fluid and sodium follow the commonly accepted ultra-endurance guidance. La Clinique du Coureur — Fuelling in trail running
- Course, aid stations and cut-offs — taken from the event's official rules, which prevail in case of any discrepancy. Official site — Sean O'Brien 100K
Weather for Sean O'Brien 100K
The weather for Sean O'Brien 100K will appear here as soon as the forecast models reach that date, around five days before the start: feels-like temperature, rain, snow, wind and storms, section by section and at your passage time.
Detailed weather for Sean O'Brien 100K, hour by hour on the courseFrequently asked questions
How many checkpoints?
Sean O'Brien 100K has 12 checkpoints: 10 aid stations and 2 checkpoints with undocumented contents. Details are in the two tables above.
What's the longest segment without aid?
The one leading to Finish: 11.8 km and 255 m elevation gain. That's the one to load up for first.
How do I find the exact location of an aid station?
The Google Maps icon in the “Access” column opens the aid station's location: handy for planning your crew's routes.
What distance and elevation gain?
Sean O'Brien 100K is 99 km long with 4000 m of elevation gain.
How long to finish?
With a UTMB Index of 600 (average runner), the estimated time is around 15h17 for Sean O'Brien 100K.
What's the weather forecast?
The weather for Sean O'Brien 100K will be published on this page around five days before the start, once the forecast models reach the race date. It will be detailed section by section: feels-like temperature, rain, snow, wind and storms.
Want to stack the odds in your favor for Sean O'Brien 100K?
In 2 minutes, RAVIT generates your complete plan: segment-by-segment time, carbs, water and sodium at every aid station, printable roadbook.
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