Bracing for a record El Niño: Climate scientist Dr. Daniel Swain

Summary

Climate scientist Dr. Daniel Swain says California is entering an exceptionally strong El Niño, increasing the odds of a very wet winter. The event is driven by warming in the equatorial Pacific, and its effects on California typically lag the ocean warming. Swain expects the greatest impacts from December through March.

He stresses that El Niño does not guarantee specific weather, but says this event’s strength and pattern make heavy precipitation more likely across central and Southern California, potentially extending north to the Bay Area, Sierra Nevada, and possibly the North Coast.

Coastal risks

The immediate concern is coastal flooding and erosion. Warm ocean water and coastal Kelvin waves can temporarily raise sea level by roughly six inches to a foot, on top of the long-term rise already experienced along California’s coast. Swain says coastal damage is already affecting homes and transportation routes in Southern California and may worsen.

He considers the governor’s state-of-emergency declaration a reasonable opportunity to prepare before the main winter impacts arrive—not a claim that disaster is certain.

Housing and risk management

The discussion also examines where people live and how the state manages risk. Californians face exposure to wildfire, flooding, or both, while housing costs can push people toward more hazardous areas. Swain’s view is that California should reconsider new construction in known high-risk locations, while acknowledging that relocating the millions already living there is neither practical nor simple.

He notes that wildfire insurance costs have risen as private insurers account for losses, whereas federally subsidized flood-insurance rates generally do not respond to seasonal forecasts. He also says California’s flood-risk planning is less developed than its approach to wildfire and earthquake risks.

Water supplies and climate impacts

El Niño could bring both danger and benefit for water supplies. A wet winter may reduce the risk of shortages the following summer, but it also raises flood risks.

Swain explains that California’s water system was built around gradual snowmelt replenishing reservoirs. Warming is reducing snowpack or causing it to melt earlier, while making the atmosphere thirstier. Even without a major fall in average precipitation, greater swings between wet and dry periods are making water planning harder.

Swain also warns that El Niño’s release of stored ocean heat is likely to contribute to exceptionally high global temperatures the following year. A wet winter followed by hotter, drier conditions could increase wildfire risk.

His central message is to use the advance warning to prepare—checking local flood and coastal risks, considering travel and power-outage plans, and strengthening readiness—rather than treating the forecast as a guarantee of catastrophe.

Presenters and contributors

• Host: Beth Ruyak
• Guest: Dr. Daniel Swain
• Production credits named in the program: Srishti Prabha, Jordan Patterson, Monty Moran, Phil Villon, Nick Norton, Carter Wells, Patrick Stewart, Lauren Flynn, Nick Masser, Peter Grayson, David Todd, Bryn Jura, Kelsey Rodriguez, Nicole Adderhold, Jeff Glasser, Chris Argentieri, Terry Tang, Anna Magazanian, and Darius Derakshani.