Red Bluff is a city in and the county seat of Tehama County, California, United States. The population was 14,710 at the 2020 census, up from 14,076 at the 2010 census. It is located 131 miles north of …Red Bluff is a city in and the county seat of Tehama County, California, United States. The population was 14,710 at the 2020 census, up from 14,076 at the 2010 census. It is located 131 miles north of Sacramento, 31 miles south of Redding, and it is bisected by Interstate 5. Red Bluff is situated on the banks of the upper Sacramento River.