San Jacinto is located at 33°47'2" North, 116°57'28" West (33.783889, -116.957778).
According to the United States Census Bureau, the city has a total area of 25.29 mi2 (65.49 km2). 24.91 mi2 (64.51 km2) of it is land and 0.38 mi2 (0.97 km2) of it is covered by water. The total area is 1.49% water.
San Jacinto is located in the Pacific Standard Time (PST) timezone, GMT-08:00. It observes Daylight Saving Time (DST).