A particularly intense El Niño phenomenon is set to transform the winter landscape across the western United States, with climate scientists warning that California could face unprecedented rainfall and flooding. Forecasts indicate that this “super” El Niño, characterised by significantly elevated sea surface temperatures, will intensify in the upcoming fall and winter months, lasting until early spring 2027.
Understanding El Niño and Its Impacts
El Niño is a recurring climate event that occurs when warmer waters in the equatorial Pacific disrupt typical weather patterns. This year’s occurrence is labelled as a “super” El Niño, a classification given when sea temperatures rise by at least 2°C. According to the US National Oceanic and Atmospheric Administration (NOAA), this could be the most potent El Niño event of the century, with models suggesting a 70% to 100% chance that California will experience above-average rainfall along its coastline.
Daniel Swain, a climate scientist from UCLA, highlighted the unpredictable nature of El Niño during a recent virtual town hall hosted by California state senator Mike McGuire. While he acknowledged that El Niño does not guarantee specific outcomes, he noted that a strong event like the one being predicted significantly increases the likelihood of a wet winter. “This will likely lead to an uptick in coastal flooding, particularly during severe storm events or king tides,” Swain explained.
Historical Context of El Niño in California
California has faced devastating consequences from El Niño events in the past. The catastrophic winter of 1982-83 saw 33 oceanfront homes destroyed and around 3,000 residences damaged, according to data from the California Coastal Commission. A subsequent El Niño in 1997-98 resulted in massive flooding and 17 fatalities. More recently, the 2015-16 El Niño brought record coastal erosion to the state’s beaches.
Mark Merrifield, from the Scripps Institution of Oceanography, noted, “With less beach in front of the coastline, the waves will have an even greater impact on the shoreline, increasing the likelihood of flooding and cliff undercutting.” The historical patterns of El Niño’s destructive potential underscore the need for vigilance and preparedness.
Current Drought Situation and Future Risks
While the impending El Niño may bring substantial rainfall to California, it is unlikely to completely alleviate the ongoing drought affecting the southwestern United States, where many reservoirs are at critically low levels. Dr. Joel Lisonbee, a senior associate scientist at the University of Colorado Boulder, cautioned against assuming that El Niño will resolve the drought, stating, “It would have to be exceptionally wet, which could also mean flooding and the associated destruction and potential loss of life.”
In addition to California, other regions across the Gulf and East Coasts, stretching from Florida to the mid-Atlantic, are facing elevated risks of increased precipitation. NOAA data suggests that central and southern Florida typically see more severe weather during El Niño years, including heightened tornado activity and flooding. The 1998 El Niño winter, for instance, resulted in an outbreak of strong tornadoes that claimed 42 lives and caused over $100 million in damages.
Preparing for Uncertainty
Experts warn that the effects of El Niño can vary significantly, not only between different events but also across geographical regions. While some El Niños have led to hurricanes and heavy rainfall, others have caused extreme heat and drought conditions. Merrifield emphasised that although this is a natural cycle, the potential temporary rise in sea levels from the super El Niño offers a stark glimpse into the future impacts of climate change.
“This El Niño presents a valuable opportunity to identify vulnerabilities across the state and strategise on how to adequately prepare,” he said. “It also serves as a sobering reminder of what we can expect in the face of climate change.”
Why it Matters
The anticipated super El Niño underscores the urgent need for proactive measures in the face of climate change. As California braces for potential winter flooding and extreme weather, the situation highlights the broader implications for climate resilience and infrastructure readiness. By understanding and preparing for these natural phenomena, communities can mitigate risks and protect lives in an era of increasingly unpredictable weather patterns. The challenges posed by this super El Niño are not just a matter of local concern; they signal the pressing need for comprehensive climate action and sustainable practices that safeguard our future.