to 31.7 °C). Summers (June–August) can be very hot with temperatures in the 80s to 100s °F (26.7 to 42.8 °C). Fall (September–November) temperatures start in the 80s to 100s °F (26.7 to 42.8 °C) but cool down significantly by November to the 40s to 70s °F (4.4 to 26.1 °C). Windy conditions are common. Nearby cities and communities Tracy (San Joaquin County) - 4.2 miles Livermore (Alameda County) - 15.6 miles Byron (Contra Costa County) - 9.2 miles Discovery Bay (Contra Costa County) - 14.8 miles Demographics The 2010 United States Census reported that Mountain House had a population of 9,675. The population density was . The racial makeup was 3,467 (35.8%) White, 903 (9.3%) African American, 45 (0.5%) Native American, 3,830 (39.6%) Asian, 71 (0.7%) Pacific Islander, 663 (6.9%) from other races, and 696 (7.2%) from two or more races. Hispanic or Latino of any race were 1,637 persons (16.9%). The Census reported that 9,675 people (100% of the population) lived in households, 0 (0%) lived in non-institutionalized group quarters, and 0 (0%) were institutionalized. There were 2,807 households, out of which 1,676 (59.7%) had children under the age of 18 living in them, 1,985 (70.7%) were opposite-sex married couples living together, 227 (8.1%) had a female householder with no husband present, 151 (5.4%) had a male householder with no wife present. There were 186 (6.6%) unmarried opposite-sex partnerships, and 31 (1.1%) same-sex married couples or partnerships. 299 households (10.7%) were made up of individuals, and 18 (0.6%) had someone living alone who was 65 years of age or older. The average household size was 3.45. There were 2,363 families (84.2% of all households); the average family size was 3.73. The population was spread out, with 3,351 people (34.6%) under the age of 18, 501 people (5.2%) age 18 to 24, 3,780 people (39.1%) ages 25 to 44, 1,676 people (17.3%) ages 45 to 64, and 367 people (3.8%) who were 65 years of age or older. The median age was 31.4 years. For every 100 females, there were 98.9 males. For every 100 females age 18 and over, there were 94.2 males. There were 3,237 housing units at an average density of , of which 2,205 (78.6%) were owner-occupied, and 602 (21.4%) were occupied by renters. The homeowner vacancy rate was 4.9%; the rental vacancy rate was 5.6%. 7,444 people (76.9% of the population) lived in owner-occupied