When it comes to El Niño, it’s best to be prepared
- UC Irvine researchers are tracking a looming El Niño event in the Pacific Ocean.
- The phenomenon could bring heavy surf, higher-than-usual tides and abundant rainfall, leading to flooding.
- Public health specialists offer advice on how to protect yourself and your family in the event of extreme weather originating with El Niño.
El Niño is a periodic warming of the tropical Pacific Ocean in the summer and fall that can cause above-average rainfall in the U.S. Southwest the following winter and spring. The temperature of the water along the equator to the west of South America this year is, as the kids would say, “giving El Niño,” but does that mean we should start pulling rain gear out of the bins? UC Irvine atmosphere and climate expert Jin-Yi Yu says maybe yes and maybe no.
“The 2026 El Niño has now reached the ‘very strong’ or ‘super’ El Niño category,” says Yu, professor of Earth system science. “The latest sea surface temperature anomalies in the tropical Pacific Ocean have crossed the threshold associated with a very strong El Niño, and current forecasts indicate that the event will continue to strengthen through the fall.”
According to the National Oceanic and Atmospheric Administration, as of Sept. 21, the sea surface temperature in a region of the central Pacific Ocean is 3.11 degrees Celsius above average, breaking a previous record of 3.08 degrees. One NOAA computer model predicts water temperature to peak near 4 degrees Celsius above average in November.
What does it mean to have seawater temperatures at this level for months on end? Yu says we had a super El Niño as recently as 2015-16, and there was a lot of speculation in the media about a wet winter to follow, but it didn’t materialize. People had their umbrellas and rain boots out and ready, but the outsized precipitation never came.
“The [El Niño Southern Oscillation] research community generally expects this to become one of the strongest – and possibly the strongest – El Niños in the modern observational record,” Yu says. “An interesting remaining question is whether it could even rival or exceed the exceptionally strong 1877-78 El Niño, although estimates of that historical event are more uncertain.”
What this means for California winter rainfall is not clear. A stronger El Niño generally increases the likelihood of atmospheric circulation patterns favorable for a wet winter in Southern California, but it does not guarantee one.
“The evolution of the 2026 event has some important similarities to the 2015-16 super El Niño, which was also expected to bring very heavy rainfall to Southern California but ultimately did not,” Yu says. “So even if the 2026 El Niño becomes the strongest on record, we should still be cautious about saying that Southern California will necessarily experience an exceptionally wet winter.”
According to him, scientists these days are having a difficult time using El Niño as a predictor of heavy winter rain in California because global warming in the 21st century prompted the development of two companions to El Niño. In addition to warming water off the coast of equatorial South America, another mass of warm water has been cropping up along the equator in the central Pacific Ocean. And on top of that, Yu has been tracking a “blob,” another large patch of abnormally high-temperature seawater, in the Gulf of Alaska.
He says his team has identified four possible factors giving rise to the central Pacific El Niño. Two of them are related to human activities: global warming and deforestation in Southeast Asia. (Yu says that when his group ran computer simulations removing trees from places like Indonesia and Malaysia, a strong central Pacific El Niño would ensue.) The two nature-driven factors are 1) a warming and cooling trend in the Atlantic Ocean that operates on a 60-to-80-year cycle which affects air circulation over the Pacific Ocean; and 2) the fact that we are entering a “very active 11-year solar cycle phase” in which sunspot activity influences the frequency and severity of El Niño events.
In other words, because of three masses of heated water in the Pacific Ocean this year, the equatorial portions and the blob to the north, we have the potential for a super El Niño, but the question remains as to whether the jet stream will be pushed to the south as in previous occurrences to bring Southern California a heavy dose of winter rain.
Preparing for El Niño impacts
Many residents of Southern California may be asking if El Niño effects are already here. Around Labor Day weekend, a succession of large storms in the Pacific Ocean – the kind we’re used to seeing during hurricane season in the Atlantic and Gulf of Mexico – pushed heavy surf toward the Golden State’s southern coastline. News reports of eroding beaches and luxury homes collapsing into the waves ran around the clock.
UC Irvine is home to some of the world’s leading researchers studying the impact of climate change on beaches and inland areas that are prone to flooding. Brett Sanders, Chancellor’s Professor of civil and environmental engineering, predicts, “The El Niño will bring us another round of high wave energy in winter, most likely between December and February, along with the highest tides we’ve had in years.”
He says there’s a decent chance we’ll set records for high tides that could result in significant flooding of low-lying areas along the coast.
“The latest seasonal forecast models are also pointing to a higher chance of a wet winter marked by heavy rainfall,” Sanders adds. “Flood control districts across California are getting prepared by cleaning out reservoirs, debris basins and flood channels that protect communities from storm damage. Unfortunately, protection is not absolute, and overtopping of these systems is always a possibility with extreme weather.”
What can you do to safeguard yourself and your family?
In addition to flexing its research might toward understanding the causes and effects of large weather and climatic anomalies such as El Niño, UC Irvine offers a deep bench of professionals who are examining the potential threats to human health that are related to the events.
Bernadette Boden-Albala, founding dean of the Joe C. Wen School of Population & Public Health, regularly informs communities – via in-person interactions and through the news media – about the often-overlooked health considerations people should address before the next major storm, power outage or flood.
“Disaster preparedness is public health preparedness. The things we do before a storm can determine how well we’re able to protect our health during and after it,” she says.
While emergency readiness often focuses on water, flashlights and batteries, UC Irvine experts encourage people to think about the health needs that can become urgent when normal routines are disrupted:
- Check medications: Make sure prescriptions are stocked in case pharmacies close or roads become difficult to navigate.
- Prepare for power outages: Consider medications, medical equipment and food that require electricity or refrigeration and form a backup plan. Have on hand items like flashlights, battery-powered lanterns, radios, portable power banks for phones and devices, car chargers for phones, and coolers and ice packs for refrigerated medications.
- Avoid flooded areas: Saurabh Chatterjee, a professor in the Center for Occupational & Environmental Health, says floodwater doesn’t just lead to drowning – it can contain sewage, bacteria, viruses and other contaminants that can cause illness. Waterborne infections can become more common in areas affected by flooding, so avoid walking or driving through floodwater whenever possible.
- Be ready to lend extra help to those who need it most: Older adults, people with disabilities, persons living with dementia, individuals who live alone and those with medical needs may confront additional challenges during an emergency.
- Keep health information accessible: Have medication lists, emergency contacts and important health information available if you need to leave home or lose power.
- Consider more than just the emergency kit: Ask what your household needs to remain healthy if transportation, food access, electricity or medical care were temporarily unavailable.
“People living with dementia and their caregivers can face unique challenges during an emergency, yet there are currently no emergency preparedness guidelines or training specifically designed for them,” says Karen Lincoln, director of UC Irvine’s Center for Environmental Health Disparities Research. “Preparing for a disaster means thinking beyond food, water and medications – it means thinking about how to reduce confusion, anxiety and distress when familiar routines are suddenly disrupted. Having familiar comfort items, a simple activity, a written reminder of daily routines and information about what helps calm a person can make an emergency less overwhelming.”