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Lake Sonoma 100K, 50K, TS Half Marathon logo

Lake Sonoma 100K, 50K, TS Half Marathon

Sat, Apr 11, 2026, 5:00 AM PDT

Location
Geyserville, CA
3227 Stewarts Point-Skaggs Springs Rd, 95441
Open in Maps
Type
TRAIL
Official registration

Sign up and verify details on the organizer’s official page.

At a glance

Embrace the challenge of Lake Sonoma's relentless trails, stunning views, and a vibrant celebration with fellow runners.

  • Fun
  • Scenic
  • Festive

Who it's for

  • Women’s Race

Great for: casual, fun-first runners, runners training for a serious effort

Less ideal for: first-time racers without recent mileage, pure PR-chasing on a bare course

The Lake Sonoma 100K, 50K, and Trail Sisters Half Marathon offer a challenging and scenic trail experience in Geyserville, California. Runners will navigate relentless rolling hills, beautiful single track, and enjoy expansive lake views. The 100K features a significant climb up Pritchett Peak, while the 50K promises a rewarding downhill finish. The event culminates in a celebratory gathering with wine and charcuterie, fostering community among participants. The Trail Sisters Half Marathon provides a supportive, women-only environment for all abilities.

What to expect

  • Tackle challenging, relentless rolling hills on beautiful single track trails.
  • Enjoy scenic lake views and a rewarding downhill finish on the 50K course.
  • The Trail Sisters Half Marathon offers a supportive, women-only experience.

Standout details

  • Celebration with wine and charcuterie
  • Trail Sisters Half Marathon (women only)
  • Full livestream coverage
  • Challenging climbs and scenic lake views

Auto-drafted from the public listing — confirm details on the official event page before signing up.

Distances & registration

3 options

Registration for all distances is through the official signup link above.

  • 13.1 Miles

    Sat, Apr 11, 9:30 AM PDT · From $117.60

    Opens Oct 1, 2025, 2:00 AM PDT · Closes Apr 10, 2026, 7:59 PM PDT

  • 50K

    Sat, Apr 11, 7:30 AM PDT · From $197.10

    Opens Oct 1, 2025, 2:00 AM PDT · Closes Apr 10, 2026, 7:59 PM PDT

  • 100K

    Sat, Apr 11, 5:00 AM PDT · From $295.00

    Opens Oct 1, 2025, 2:00 AM PDT · Closes Apr 10, 2026, 7:59 PM PDT

The course

  • Trail
  • Hilly

Vibe Check

Serious Test

Trail + hills, longer distance

ultra distance, mostly trail, mountainous area, typically mild weather

  • Mostly trail

Based on typical seasonal and area patterns — not a course map or official forecast.

From the organizer

Join us in Healdsburg, California, on April 11th 2026 for the TERREX Lake Sonoma 100K, 50K, and Trail Sisters Half Marathon! We are excited to have adidas TERREX back as our presenting partner!

We are stoked to team up with Mountain Outpost to bring you full livestream coverage, athlete panels, interviews, and commentary from special guests!

Lake Sonoma 100K

The 100K course will start with a climb up Pritchett Peak with a water only stop at the top. Once you reach the summit you’ll head back down toward the Lake Sonoma Visitors Center and then up to the hill to South Lake Trailhead where you’ll embark on an out and back of the original old school LS course and then back down the hill to the finish. It’s the same great Lake Sonoma Relentless experience, only this time with a big climb to kick it all off!

Lake Sonoma 50K

It’s not worth it unless you have to work for it! The 50k start is located in the green space next to the Lake Sonoma Visitor Center (you can’t miss it). After a short road section to get the field spread out  the course then continues onto beautiful rolling single track trails. You will continue past South Lake, Island View, Warm Springs Creek, Wulfow, Liberty Glen and the Bummer aid stations, finally crossing the scenic lake bridge. Remember to save some juice for the last few miles, as you have a screaming downhill towards the finish. The race starts at 7:30am.

Don’t forget to enjoy the views! … and be sure to take a dip in the water to cool off. (but don’t drink!)

Trail Sisters Women's Half Marathon

The Trail Sisters (TS) Half Marathon is a women’s only event. It was created to foster encouragement and camaraderie amongst all abilities and experience levels. This out and back course starts with steep trail ascent to South Lake Trailhead, but also provides a speedy descent to the finish. True to its label, you can expect relentless rolling hills that will challenge your mind and body. Lucky for you though, you will share the journey with a community of supportive Trail Sisters to help you through! You will have 4 and half hours to complete the half marathon course.

Come Celebrate!

Lake Sonoma isn’t just a race event, it’s a celebration. We always complete the weekend with a Celebration and Thank You event at Coyote Sonoma in Healdsburg, CA. Everyone involved with the event is invited to enjoy wine, charcuterie, and share stories from the weekend.

See you on that start line! Gina & Justin LS Race Directors

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