Boyes Hot Springs is a census-designated place in Sonoma Valley, Sonoma County, California, United States. The population was 6,656 people at the 2010 census. Resorts in Boyes Hot Springs, El Verano, Fetters Hot Springs, and Agua Caliente were popular health retreats for tourists from San Francisco and points beyond until the middle of the 20th century because of the geothermic hot springs that still well up from deep within the Earth.