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SACRAMENTO, Calif. – While California’s climate has always swung between dry and wet conditions, the past five years have proven what climate science has predicted: California must be prepared for extreme weather events of all kinds, even simultaneous drought and flood conditions.
As the new Water Year gets underway, Lake Oroville, the State Water Project’s largest reservoir, is currently 109 percent of average for this date, however there is uncertainty about conditions this winter. The latest outlook from the National Oceanic and Atmospheric Administration’s (NOAA) Climate Predication Center shows a 71 percent chance of La Niña conditions this fall, decreasing to a 54 percent chance in December through February. La Niña events have historically resulted in more dry than wet years, but research also suggests that even as the climate grows hotter and drier overall, the precipitation that California does receive will arrive in stronger storms, increasing the risk from flooding.
“There is no such thing as a normal water year in California,” said DWR Director Karla Nemeth. “Just in the past two winters, deceptively average rain and snowfall totals statewide masked the extremely dry conditions in Southern California that contributed to devastating fires as well as flood events across the state from powerful atmospheric river events. California must be ready to respond to emergencies from droughts to floods to fires.”
Last winter, extremely dry fall conditions in Southern California fueled the destructive Eaton and Palisades fires just weeks before the typical peak of atmospheric river storm activity in California. DWR, alongside the Governor’s Office of Emergency Services, CAL FIRE, Caltrans, the California Geological Survey and the California Conservation Corps worked around the clock to protect downstream communities and watersheds as part of the state’s largest watershed protection mission to keep hazardous material from contaminating local water supplies and waterways.
Extreme flooding will remain a critical concern moving into this water year as a warmer atmosphere drives more moisture through more powerful storms. DWR’s flood operations staff will be holding meetings with emergency response personnel across the state in the coming weeks to make sure the state and communities are prepared to respond. DWR has over 4.3 million sandbags and 191 flood fight materials containers pre-positioned for quick deployment across the state if needed.
“The past decade has clearly demonstrated the need to prepare for extremes,” said State Climatologist Dr. Michael Anderson. “A dramatic flood year in 2023 was followed by two years with large spatial disparities. While our water supplies are in a good position heading into the new water year, we will be watching closely for dry and wet extreme conditions that can pose hazards statewide.”
California is also starting this water year with more groundwater data than ever before, helping groundwater sustainability agencies and communities monitor conditions in their region to promote long-term sustainability and protect drinking water supplies against the impacts of climate change. Over the course of 2024, the state received average precipitation, helping sustain natural and managed recharge efforts after the exceptionally wet 2023. These last three years (2023, 2024, and 2025) have seen continued increases in groundwater storage.
California’s water year runs from October 1 to September 30 and is the official 12-month timeframe used by water managers to compile and compare hydrologic records.
For more information on California’s current hydrological conditions, visit https://cww.water.ca.gov.
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