Event Overview
| Date | Oct 17-18, 2026 |
|---|---|
| Location | Lake Sonoma, Geyserville, California, USA |
| Format | Fixed-Distance |
| Terrain | Trail |
| Region | North America |
| Distance / duration | 100.5 mi |
| State / area | California (CA) |
| Course model | Loop |
| Edition note | Both official pages give October 12 as the online entry deadline, but disagree on the time zone: the organizer says 11:59 PM MT and UltraSignup says 11:59 PM PT. Confirm the applicable deadline before relying on the later time. |
| Elevation gain | Estimated 25,058 ft |
| Cutoff | 36 hours |
| Start | 5:00 AM Saturday |
| Highlights | Inaugural 100-Miler, Lake Sonoma |
Course & Terrain
Two 50.25-mile loops from Lake Sonoma Recreation Area, including the Pritchett Peaks climb and lakeside singletrack.
Entry & Logistics
| Registration and fees | Check the official event website for current availability, deadlines, prices, taxes, and refund terms. |
|---|---|
| Crew / pacers | One pacer allowed after mile 50 or after dark; bib and waiver required. Warm Springs crew access is restricted to the second pass. |
| Logistics note | Final finish is Sunday at 5:00 PM. Follow orange course markers and carry a headlamp. Pritchett Peaks access is limited to race day. |
Why This Race Matters
Aravaipa Running and Healdsburg Running Company launch this festival in October 2026 with Tropical John Medinger. The new 100-miler joins the established Lake Sonoma 50 Mile, which moves to the autumn festival; the 50-mile course records do not apply to this inaugural 100-mile race.
Historical benchmark notes in the directory record (verify current records with the linked official sources):
- Inaugural 100-mile edition in 2026; no previous course record.
Preparing for a Race Like Sonoma Fall Classic 100 Mile
The 100-mile race guide covers the format as a whole. These guides go deeper:
- Walking strategy for ultramarathons: When and how to walk by terrain, effort and cutoffs.
- Crew and aid-station strategy: Crew tables, aid stops, drop bags and runner preferences.
- Gut training for ultrarunners: A six-week practice sequence for race-day fueling.
- Tapering for ultramarathons: Plan the taper and race week around your own recovery.
Planning Notes
- Treat intermediate cutoff gates as part of the course. Build enough margin for aid stops and late-race slowdown, and verify every current gate in the official rules.
- Train for terrain-specific fatigue. Technical trails and mountain courses demand downhill durability, hiking efficiency, and reliable night lighting.
- The directory does not mark this as having simpler logistics. Confirm qualification, terrain, support, registration, medical, and withdrawal requirements before planning around it.
Related Preparation
- Compare verified US 100-mile races
- Compare this race in the full 2026 calendar
- Open the 100-Mile format guide
- Open the Fixed-Distance format guide
- Compare all race formats
- Use the timed-race pace calculator
- Plan checkpoint arrivals and cutoff buffers
- Build a crew and drop-bag plan
- Build a race-specific gear checklist
Verification & Sources
Verification scope: the listed edition's date, location, format, and available logistics were checked against the event-specific official sources below during the directory review dated October 12, 2026. Organizers can revise details after review.
- Official 2026 course, schedule and rules — https://www.aravaiparunning.com/california-races/sonoma/
- Organizer’s 2026 registration — https://ultrasignup.com/register.aspx?did=133833
- Organizer’s announcement of the new festival — https://www.aravaiparunning.com/2025/12/24/sonoma-fall-classic-aravaipas-newest-race-in-northern-california/
- Multiday Running event directory review scope: October 12, 2026.