Diablo Grande is a census-designated place in Stanislaus County, California. It is a gated bedroom community nestled in the Diablo Range, whence it gets its name. Diablo Grande sits at an elevation of 1,535 feet. It is about 9 miles southwest of Patterson. The 2010 United States census reported Diablo Grande's population was 826. The 2018 estimated p…Diablo Grande is a census-designated place in Stanislaus County, California. It is a gated bedroom community nestled in the Diablo Range, whence it gets its name. Diablo Grande sits at an elevation of 1,535 feet. It is about 9 miles southwest of Patterson. The 2010 United States census reported Diablo Grande's population was 826. The 2018 estimated population was 1,200.