page_title: Ventura River
section_title: Climate
hierarchical_section_title: Ventura River / Physical geography / Climate
caption_attribution_description: Ventura River downstream of Santa Ana Bridge in 2011.
context_page_description: The Ventura River, in western Ventura County in southern California, United States, flows 16.2 miles from its headwaters to the Pacific Ocean. The smallest of the three major rivers in Ventura County, it flows through the steeply sloped, narrow Ventura Valley, with its final 0.7 miles through the broader Ventura River estuary, which extends from where it crosses under a 101 Freeway bridge through to the Pacific Ocean.
context_section_description: Rainfall varies geographically, seasonally, and from year to year. Median annual precipitation is 14.12 inches or 359 millimetres in the lower watershed, 19.20 inches or 488 millimetres in the middle watershed, and 28.74 inches or 730 millimetres in the upper watershed. However, even in the subhumid upper basin, rainfall is infrequent – falling on as few days in a year as in hot, arid Phoenix, Arizona – but when rain does fall it can be extremely heavy with totals of 20 inches or 510 millimetres in a week not uncommon in the middle and upper basins. Consequently, cycles of drought and flood are the norm: as an illustration, in the main settlement of Ojai since 1906, 67 percent of the years have had less than the mean rainfall.
  Many parts of the Ventura River stream network are typically dry during much of the year. Surface water readily disappears underground in some stream reaches (segments); in others, groundwater regularly feeds streamflow.
caption: Ventura River downstream of Santa Ana Bridge, 2011. Photo courtesy of Scott Lewis.
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