The Cleveland National Forest encompasses 460,000 acres/720 sq mi (1,900 km2) of inland montane regions—approx. 60 miles from the Pacific Ocean—within the counties of San Diego, Riverside, and Orange, California. The landscape varies somewhat, with mostly chaparral canyons, arroyos and high desert, but dotted with meadows and oak and conifer forests. Near water sources, riparian environments and perennial aquatic plants attract native and migratory wildlife, such as at San Diego’s man-made Lake Cuyamaca. A generally warm and dry, inland-Mediterranean climate prevails over the forest, with the cooler months producing morning frost and snowfall. It is the southernmost U.S. National Forest of California. The area is administered by the U.S. Forest Service, a government agency within the United States Department of Agriculture, and is locally overseen by the Descanso, Palomar and Trabuco Ranger Districts.

San Diego County, officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fifth-most populous in the United States. Its county seat is San Diego, the second-most populous city in California and the eighth-most populous city in the United States. It is the southwesternmost county in the 48 contiguous United States, and is a border county. It is also home to 18 Native American tribal reservations, the most of any county in the United States.