The Western monarch butterfly is found across coastal California in the winter.
In Monterey County, the largest population of overwintering monarch butterflies can typically be found at the Pacific Grove Monarch Sanctuary at 250 Ridge Road, Pacific Grove CA 93950.(https://www.google.com/maps/place/250+Ridge+Rd,+Pacific+Grove,+CA+93950/@36.6273716,-121.913344,3730m/data=!3m1!1e3!4m6!3m5!1s0x808de13953ee0c2d:0xf4e360ddf83681c6!8m2!3d36.6263232!4d-121.9298523!16s%2Fg%2F11bw4nfz1y?entry=ttu&g_ep=EgoyMDI1MDUwNy4wIKXMDSoASAFQAw%3D%3D) For more information about the Monarch Sanctuary, including hours, parking, pet policy, and the latest monarch count, visit www.pgmuseum.org/monarchs.(http://www.pgmuseum.org/monarchs)
Other popular overwintering sites are Natural Bridges State Beach (https://www.parks.ca.gov/?page_id=541)in Santa Cruz, and the Pismo State Beach Monarch Butterfly Grove (https://www.parks.ca.gov/?page_id=30273)just south of San Luis Obispo.