The
alluvial valley is formed by the
Santa Ana River and its tributaries. The Pomona Valley is separated from
San Gabriel Valley to the west by the northeastern end of the
San Jose Hills, running approximately along
State Route 57. The eastern boundaries are the Jurupa Hills and the
Cajon Pass, (the eastern end of the
San Gabriel Mountains) running near
Interstate 15, which separates the Pomona Valley from the
San Bernardino Valley. The northern boundary is the
San Gabriel Mountains. The
Chino Hills are the southern boundary that separates the Pomona Valley from northern Orange County. Historic
U.S. Route 66 runs east-west across the north side of Pomona Valley. San Antonio Creek runs right through the center of the valley dividing the valley into west and east, and also acts as a section of the border between
Los Angeles County and
San Bernardino County. It originates from the San Gabriel Mountains watershed around
Mount San Antonio (known locally as Mt. Baldy) and joins the Santa Ana River south of Chino. The Pomona Valley ranges from the city of
San Dimas from the far west to
Rancho Cucamonga to the far east portion of the valley.
Climate The Pomona Valley experiences a
Mediterranean Climate. In contrast to much of the
Greater Los Angeles Area, The Pomona Valley can get much hotter summers with high temperatures ranging from the triple digits. Due to its elevation ranging from 800 to 2200 feet, winters in the Pomona Valley can also get cold. Trace amounts of snowfall can occur anywhere above 1500 feet. On the valley floor, average rainfall amounts range anywhere from 12 to 16 inches. Foothill communities can get anywhere from 14 to 18 inches of rain a year. In the fall (fire season),
Santa Ana Winds can occur giving strong offshore winds from the
Cajon Pass. {{Weather box ==Demographics==