Marin's iconic ridgelines in a spirited 28K with Bay Area views in every direction
The Big Alta 28K takes place on March 21, 2027 in San Rafael, CA.
The Big Alta 28K is 17.4 miles with 4,180 ft of elevation gain.
No — The Big Alta 28K uses open registration; no lottery is required.
Yes, crew is allowed at The Big Alta 28K. Crew can access 2 of the 3 locations listed on this page.
No, pacers are not allowed at The Big Alta 28K.
No, The Big Alta 28K does not allow drop bags.
The Big Alta 28K has 1 aid station along the course.
The overall cutoff for The Big Alta 28K is 5h30m. Individual cutoffs for 2 of the 3 locations listed on this page are published below.
The Big Alta 28K has published cutoff times at 2 points on the course. Each one is listed on this page with its location, distance and cutoff.
Other trail races within 100 miles
The Big Alta 28K is a spirited single-loop trail race through Marin County's iconic ridgeline terrain. Despite its approachable distance, the course delivers 3,900 feet of climbing through open grassland meadows, oak woodlands, and exposed fire road ridges. The route summits both Loma Alta and Big Rock Ridge — the two highest points in Marin County — with panoramic views of the entire San Francisco Bay Area. A perfect entry point to Bay Area trail racing for newer runners, or a hard-charging effort for experienced athletes.
Some ultra experience recommended
San Rafael, CA, United StatesMarch 21, 2027
The Big Alta 28K is a loop trail race in San Rafael, CA, United States, held on March 21, 2027. The course covers 17.4 miles, climbs 4,180 ft, and has a 5h30m cutoff.
| Location | Mile | Elevation | Cutoff | Crew |
|---|---|---|---|---|
Start Start | 0.0 | 79 ft | — | Crew |
Aid Stn - Big Rock Aid Station | 8.8 | 663 ft | 2h45m10:45 AM | |
START/FINISH - Marinwood Community Ctr Finish | 17.4 | 79 ft | 5h30m1:30 PM | Crew |
Aid station details for this race are still being filled in. Cutoffs and access rules come from the race’s own published information and can change — check the official race details before planning around them.
Sign in for race-day weather at every station, points of interest, segment-by-segment analysis, pacing, and to save this race to your calendar.
Friendly, leashed dogs are allowed at the event staging area and finish line, but not on the race course.
Late March in Marin County brings variable spring conditions with morning temperatures in the 40s°F and afternoon highs reaching 55-75°F. The 5.5-hour race window keeps runners in daylight, but spring fog, breezes, and occasional rain showers are common. Exposed ridgelines on Loma Alta and Big Rock Ridge can be windy.
Spring conditions can include sun, wind, fog, and rain showers in a single day
Exposed ridge running along Loma Alta and Big Rock Ridge can be windy
No required gear specified
No recommended gear specified
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