According to the United States Census Bureau, the CDP has a total area of 2.6 square miles (6.7 km2).

This region experiences hot, dry summers and mild, rainy winters, receiving more rainfall than most areas in Metro Los Angeles due to being situated in the upslope foothill regions and experiencing orographic effects which increase precipitation.

There were 1,239 housing units at an average density of 473.3 per square mile (182.7/km2), of which 1,004 (83.8%) were owner-occupied, and 194 (16.2%) were occupied by renters.

According to the 2010 United States Census, San Antonio Heights had a median household income of $106,905, with 2.9% of the population living below the federal poverty line.

Beginning in 1958, a private residence directly north of Euclid Avenue in San Antonio Heights displayed an enormous five-point star of lights each holiday season.

[8] Traditionally the 35-foot star was lit each night between Thanksgiving and New Year's Day and was visible for miles throughout the Pomona Valley.

The star and the two-story home to which it was attached were destroyed October 25, 2003 in the Grand Prix Fire that swept through the area.

More than $20,000 was raised to assist the property owner in rebuilding the star, so a temporary replacement measuring 65 feet tall was erected with a crane during the 2003-2005 holiday seasons.

Because of this, hundreds of residents of San Antonio Heights purchased smaller stars that year and put those on their houses during the holiday season.

Ken Petschow, a commercial airline pilot who owns the property, lit the star again beginning in 2007.

The community holds three annual events: A pancake breakfast on the weekend preceding Memorial Day, a Steakfest in mid-September—both at San Antonio Park—and a Holiday Sing-Along on Christmas Eve at Local Fire Station 12.

In the California State Legislature, San Antonio Heights is in the 25th Senate District, represented by Democrat Sasha Renée Pérez, and in the 41st Assembly District, represented by Democrat John Harabedian.