Oceano is located at 35°6′10″N 120°36′41″W (35.102680, -120.611471).
Oceano is part of the 5 Cities Metropolitan Area. According to the United States Census Bureau, the CDP has a total area of 1.5 square miles (3.9 km2), of which, 1.5 square miles (3.9 km2) of it is land and 0.02 square miles (0.052 km2) of it (0.98%) is water.
Oceano's beach is the Oceano Dunes State Vehicular Recreation Area, a 1,500 acres (6.1 km2) coastal sand dune. As the only state park in California where visitors may drive vehicles on the beach, tourists are attracted from all over the United States. Activities on this beach include riding the sand dunes on all-terrain-vehicles, swimming, clamming, camping, surfing, surf fishing, hiking, and bird watching.
The 2010 United States Census reported that Oceano had a population of 7,286. The population density was 4,710.2 people per square mile (1,818.6/km²). The ethnic makeup of Oceano was 5,105 (70.1%) White, 62 (0.9%) African American, 120 (1.6%) Native American, 165 (2.3%) Asian, 7 (0.1%) Pacific Islander, 1,509 (20.7%) from other races, and 318 (4.4%) from two or more races. Hispanic or Latino of any race were 3,484 persons (47.8%).
The Census reported that 7,286 people (100% of the population) lived in households, 0 (0%) lived in non-institutionalized group quarters, and 0 (0%) were institutionalized.
There were 2,603 households, out of which 904 (34.7%) had children under the age of 18 living in them, 1,147 (44.1%) were opposite-sex married couples living together, 360 (13.8%) had a female householder with no husband present, 197 (7.6%) had a male householder with no wife present. There were 197 (7.6%) unmarried opposite-sex partnerships, and 38 (1.5%) same-sex married couples or partnerships. 680 households (26.1%) were made up of individuals and 266 (10.2%) had someone living alone who was 65 years of age or older. The average household size was 2.80. There were 1,704 families (65.5% of all households); the average family size was 3.39.
The population was spread out with 1,738 people (23.9%) under the age of 18, 747 people (10.3%) aged 18 to 24, 2,028 people (27.8%) aged 25 to 44, 1,870 people (25.7%) aged 45 to 64, and 903 people (12.4%) who were 65 years of age or older. The median age was 35.4 years. For every 100 females there were 101.9 males. For every 100 females age 18 and over, there were 100.7 males.
There were 3,117 housing units at an average density of 2,015.1 per square mile (778.0/km²), of which 1,355 (52.1%) were owner-occupied, and 1,248 (47.9%) were occupied by renters. The homeowner vacancy rate was 3.7%; the rental vacancy rate was 5.9%. 3,444 people (47.3% of the population) lived in owner-occupied housing units and 3,842 people (52.7%) lived in rental housing units.
As of the census of 2000, there were 7,260 people, 2,447 households, and 1,722 families residing in the CDP. The population density was 4,774.4 people per square mile (1,844.1/km²). There were 2,762 housing units at an average density of 1,816.4 per square mile (701.6/km²). The racial makeup of the CDP was 68.73% White, 1.12% African American, 1.29% Native American, 1.80% Asian, 0.03% Pacific Islander, 21.78% from other races, and 5.25% from two or more races. Hispanic or Latino of any race were 44.63% of the population.
There were 2,447 households out of which 38.8% had children under the age of 18 living with them, 50.2% were married couples living together, 14.8% had a female householder with no husband present, and 29.6% were non-families. 23.0% of all households were made up of individuals and 9.2% had someone living alone who was 65 years of age or older. The average household size was 2.96 and the average family size was 3.50.
In the CDP, the population was spread out with 29.5% under the age of 18, 10.2% from 18 to 24, 29.8% from 25 to 44, 20.1% from 45 to 64, and 10.4% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 97.2 males. For every 100 females age 18 and over, there were 96.3 males.
The median income for a household in the CDP was $38,014, and the median income for a family was $39,254. Males had a median income of $28,180 versus $21,310 for females. The per capita income for the CDP was $16,561. About 14.1% of families and 16.3% of the population were below the poverty line, including 22.0% of those under age 18 and 6.2% of those age 65 or over.
The environs of Oceano were the home of "Halcyon," a utopian religious community established in 1903 by the theosophical Temple of the People, based in Syracuse, New York. The group, which believed in channeling unseen electromagnetic forces in an effort to attain human perfection, constructed a number of buildings in association with their colonizing effort, including the Blue Star Memorial Temple and the Halcyon Hotel and Sanatorium.The Great American Melodrama performs original plays nightly in Oceano.
Irish poet and Celtic mythologist Ella Young's final years were spent in Oceano (she died there in 1956).
In the state legislature Oceano is in the 17th Senate District, represented by Democrat Bill Monning, and in the 35th Assembly District, represented by Republican Jordan Cunningham.
In the United States House of Representatives, Oceano is in California's 24th congressional district, represented by Democrat Salud Carbajal.