Arroyo Grande is a city in San Luis Obispo County, California, United States. The population was 17,252 at the 2010 census. Arroyo Grande is a small coastal town with historic, suburban, and rural elements located at 35°7′15″N 120°35′12″W / 35.12083°N 120.58667°W / 35.12083; -120.58667 (35.120878, -120.586799).