The Mayacamas Mountains are a mountain range located in northern California, primarily between Sonoma County and Napa County. They stretch approximately 30 miles and are known for their rugged terrain, diverse ecosystems, and scenic views. The mountains are part of the larger California Coast Ranges and are characterized by oak woodlands, chaparral, and coniferous forests. The highest peak in the Mayacamas Mountains is Mount St. Helena, which rises to an elevation of 4,342 feet. The area is popular for outdoor activities such as hiking, mountain biking, and wildlife observation. The mountains also play a significant role in the local climate, influencing weather patterns in the surrounding valleys.