St. helena is located in Napa county California with a geographic area of 5.0 square miles. The total population in St. helena is 6,049 with 49.5% male and 50.5% female. Children under age 5 represent 5.8% of the population, under age 18 equal 13.6% of the population and over age 65 is 32.0% of the population. The median household income is $103,452, per capita income is $92,408. There are a total of 2,866 housing units with 67.6% owner occupied. Education includes 7.5% of residents that are high school graduates and 61.3% with a bachelor's degree or higher. The average temperature in St. helena in the summer is 76 degrees, and in the winter 43 degrees.