The Sacramento Valley region, comprised of Sacramento, Yolo, Sutter, Yuba, Colusa, Glenn, Butte, Tehama, Shasta, and parts of Solano and Placer counties, is home to large expanses of agricultural production and rangelands, wetlands, riparian habitats, and forested foothills. Much of the region’s recreational, energy generation, and agricultural activity centers around three major river watersheds – the Feather, American, and Sacramento rivers – that converge in the Valley on their way toward the Delta. The region is also home to the state Capitol and over 950,000 of the region’s 2.4 million mostly urban residents (or 40%), many of whom live within 500-year flood plains in the Sacramento River watershed.
The Sacramento Valley will likely see average daily maximum temperatures increase by 10 ºF by end-of-century. Rising temperatures are driving more frequent and intense heat waves and fewer cooling degree days and nights in the Sacramento Valley.
Annual precipitation is expected to remain about the same on average, or increase only slightly this century, though increased variability and frequency of extreme weather events means the region will be more prone to droughts and floods. Oscillation between extremely dry and extremely wet periods make the possibility of an extreme flood event more likely. Additionally, due to increased temperatures, storms will increasingly fall as rain versus snow. Snowpack will diminish in the region, and seasonal snowmelt patterns will shift to earlier, threatening the region’s water supplies.
Earlier spring conditions, wetter winters, and drier summers will continue to contribute to increased large summer and fall wildfires. As experienced during large fire events during the last five years, fires within Sacramento Valley and in other parts of the state impact air quality.
Sea-level rise in the San Francisco Bay Area will contribute to flooding in the Sacramento Valley region, as flood waters are also likely to push ocean water into the fresher waters of the Sacramento-San Joaquin Delta.