A research team at the University of Hawaiʻi at Mānoa has built a stripped-down, ocean-only forecast model that, in hindsight tests, can spot El Niño about 15 months ahead. That same tool is now flashing warnings for a powerful event late this year. Called Wyrtki-CSLIM, the approach relies only on sea-surface temperature and sea-surface height measurements to capture two kinds of climate "memory" that help steer ENSO. If this projection holds, scientists say the event could crank up heat and rainfall extremes across the globe and pile extra stress on Hawaiʻi's reefs and water supplies.
According to University of Hawaiʻi News, the work, published in Geophysical Research Letters, showed that Wyrtki-CSLIM produced skillful Niño-3.4 forecasts out to roughly 15 months in retrospective runs. Lead author Yuxin Wang and colleagues set out to keep the model low order and physically interpretable while still grabbing the key ocean signals that tend to show up before ENSO shifts.
How the Wyrtki-CSLIM works
The study describes a cyclostationary linear inverse model that explicitly blends two types of memory in the climate system. One is the equatorial upper-ocean heat content often called Wyrtki memory. The other is the slower persistence of sea-surface temperatures outside the tropical Pacific, known as Hasselmann memory. As detailed in Geophysical Research Letters, putting those pieces together lets the system capture both recharge dynamics and remote precursors that sharpen medium-range ENSO timing and amplitude forecasts.
What the model predicts
Forecasts released alongside the study show Wyrtki-CSLIM calling for a strong El Niño to take shape toward the end of 2026, with some scenarios pushing equatorial eastern Pacific temperature anomalies above +2 °C relative to normal. That level is higher than in many purely statistical systems and lines up broadly with several dynamical model ensembles, which has scientists worried about outsized global impacts if the event materializes at that strength. Coverage of the findings appears at Phys.org.
Matthew Widlansky, associate director of the UH Sea Level Center, noted that the model "is predicting a stronger El Niño than most statistical models" while emphasizing that "all models have uncertainties." The team presents Wyrtki-CSLIM as a cheaper, more easily explained companion to heavyweight operational systems rather than a replacement. Additional press materials from the university are posted through EurekAlert!.
Operational centers had already been slowly tilting their outlooks toward El Niño in 2026. The World Meteorological Organization reports an increased chance of El Niño developing from mid-2026, and the NOAA Climate Prediction Center currently shows elevated odds of El Niño conditions through the Northern Hemisphere summer and into autumn. Those official outlooks will be updated as new data roll in.
What this could mean for Hawaiʻi
In Hawaiʻi, past El Niño episodes have gone hand in hand with shifts in seasonal rainfall, warmer offshore waters that fuel coral bleaching, and knock-on effects for nearshore fisheries and freshwater supplies. The U.S. National Climate Assessment notes that ENSO swings layered on top of background warming can magnify stress on reefs and heighten water-supply vulnerabilities across the islands. The UH Sea Level Center maintains up-to-date ENSO forecasts and monitoring tools that managers and residents can tap for planning.
The authors are open about the model's blind spots. As a linear stochastic system, Wyrtki-CSLIM can fail to capture rapid nonlinear growth from small initial disturbances and has at times underestimated past events, the Geophysical Research Letters analysis notes. Wang told University of Hawaiʻi News that better year-ahead guidance could give communities and resource managers a chance to blunt impacts, but that every El Niño plays out differently in different regions. Experts say Wyrtki-CSLIM's signals should be weighed alongside the full suite of operational dynamical and statistical forecasts.
Researchers add that the next several months will be key. Forecasters will track Niño-3.4 sea-surface temperatures, warm water volume, and wind patterns for signs that an event is truly taking shape. For regular maps and probability charts, the UH Sea Level Center and the NOAA Climate Prediction Center remain the top public resources. If Wyrtki-CSLIM keeps pointing toward a strong El Niño, that extra lead time could give planners a longer runway to prepare for the weather swings, ecological stress, and water-resource challenges that often come with major El Niño events.
