Lake Sonoma 100K / 55K
Lake Sonoma, United States • 18 Oct 2025
The Lake Sonoma 100K and 55K, also known as the California Fall Classic, is a challenging ultramarathon held at Lake Sonoma, California, set amidst the scenic wine country during harvest season. The event features two distances—100 kilometers and 55 kilometers—on demanding courses that traverse miles of single-track trails with stunning lake views. Known for its vibrant atmosphere, the race weekend offers free on-site camping, live music, and local food, wine, and beer, embodying the region's hospitality. The 100K race serves as a qualifier for the prestigious Western States Endurance Run, making it a key late-season challenge for ultrarunners seeking cooler weather and a competitive test. Visit the organization's website for the most recent information.