The last time a significant El Niño took hold, during the winter of 2023-24, it helped push global temperatures to record highs and scrambled rainfall patterns from California to the Gulf Coast. Now, federal forecasters say the tropical Pacific may be gearing up for a repeat. In its April 2026 outlook, NOAA’s Climate Prediction Center placed the probability of El Niño conditions during May through July at 61 percent, a threshold that, if crossed, would shift temperature and precipitation patterns across the United States through the rest of the year.
For farmers planting summer crops, city officials bracing for heat waves, and water managers stretched thin across the drought-prone Southwest, that number is high enough to demand attention and uncertain enough to complicate planning.
Where the science stands in April 2026
The 61 percent figure is not a single model’s guess. The Climate Prediction Center reaches its consensus by blending multiple dynamical and statistical models with real-time ocean and atmosphere observations. The physical signal at the center of the forecast is sea surface temperature in the Niño 3.4 monitoring region of the central-eastern Pacific. The North American Multi-Model Ensemble, a collection of leading climate models, shows those temperatures warming toward and above the +0.5 degrees Celsius anomaly that defines El Niño onset, with model runs converging on a warming trajectory through summer.
Independent support comes from NOAA’s Geophysical Fluid Dynamics Laboratory, whose SPEAR model ensemble points to an elevated likelihood of a moderate-to-strong El Niño by fall 2026. The CPC’s seasonal outlook for May 2026 onward explicitly ties its regional temperature and precipitation forecasts to these ENSO expectations, identifying the Pacific warming as a key driver for specific parts of the country.
One technical change worth noting: NOAA adopted a new classification framework earlier this year. The Relative Oceanic Niño Index, or RONI, updates how the agency defines El Niño and La Niña phases. That means the thresholds used in this spring’s forecast differ slightly from those applied in previous cycles, which could affect how quickly an official El Niño advisory is declared.
What El Niño historically does to U.S. summers
El Niño is not a single weather event. It is a shift in the ocean-atmosphere system that tilts the odds for entire seasons. The strength of that shift matters enormously.
A weak El Niño tends to nudge the southern jet stream slightly southward, bringing modest extra rainfall to parts of the Gulf Coast and the southern Plains while leaving much of the country close to normal. A strong event is a different animal. It can suppress Atlantic hurricane activity by increasing upper-level wind shear over the tropical Atlantic, amplify heat across the Midwest and Great Plains, and deepen drought in the Pacific Northwest by steering storm tracks away from the region.
During the 2023-24 El Niño, California saw a parade of atmospheric rivers that eased years of drought, while parts of the Ohio Valley dealt with unusual winter warmth. Summer impacts were subtler but still measurable: above-normal heat settled across the southern tier of states, and the Atlantic hurricane season, while active, produced fewer major landfalls than some models had projected. Whether a 2026 event would follow a similar script depends on its intensity and timing, both of which remain open questions.
Why uncertainty is still high
A 61 percent probability means roughly four-in-ten chances that El Niño does not materialize on schedule. Forecasters have long recognized what they call the “spring predictability barrier,” a period when tropical Pacific signals are notoriously difficult to read. Model projections that look tightly clustered in April can diverge sharply by June, and no post-April verification data are yet available to confirm whether the warming trend has accelerated or stalled.
Even if El Niño does develop, its intensity is uncertain. The CPC publishes strength probability categories that break the forecast into weak, moderate, and strong scenarios. The SPEAR ensemble leans toward moderate-to-strong, but model spread remains wide. For a farmer deciding whether to invest in an extra cutting of hay, or a reservoir manager weighing early water releases, the difference between a weak and strong event is not academic. It is the difference between a slightly wetter summer and a fundamentally reorganized weather pattern.
Regional precipitation forecasts for summer 2026 add another layer of ambiguity. The CPC’s seasonal outlook discussion ties its rainfall reasoning to ENSO expectations but stops short of granular, state-level projections. Agricultural producers and municipal water systems are left working with broad regional tilts rather than precise local guidance.
How to use a probabilistic forecast
For anyone whose livelihood or safety depends on summer weather, the practical first step is straightforward: treat the 61 percent chance of El Niño as a meaningful tilt in the odds, not a guarantee. In risk terms, it is high enough that ignoring it could be costly, but not so high that planning only for an El Niño outcome is wise.
In agriculture, that may mean staggering planting dates, diversifying crop choices, or locking in irrigation options that can cover a wider range of rainfall outcomes. For utilities, it could involve stress-testing power demand scenarios under both elevated cooling loads and potential storm-related outages. Wildfire agencies in the West may lean toward early staffing and fuel-reduction work in regions where an El Niño pattern historically delays but does not eliminate late-summer fire danger.
Local emergency managers do not need to become ENSO experts, but they do need to understand what a probabilistic forecast can and cannot say. A seasonal outlook that favors above-normal rainfall in a region does not specify which town will see flooding or which week will bring the heaviest storms. It signals that planning for higher-than-usual hydrologic stress is prudent.
The National Weather Service maintains a central portal where local offices post outlooks, briefings, and hazard information tailored to their areas. Those local products often translate national ENSO-driven signals into concrete advice about heat waves, flash flooding, or wildfire smoke that residents and businesses can act on.
What to watch over the next two months
The CPC will update its ENSO probability tables as new ocean and atmosphere data arrive through May and June 2026. Watching how that 61 percent figure shifts over the next one to two monthly cycles will offer an early signal as to whether the Pacific is locking into an El Niño pattern or drifting toward a more neutral state.
Right now, the Pacific is warming, models are leaning toward El Niño, and federal forecasters have put a number on that lean. But the atmosphere has not fully committed. The range of plausible outcomes for summer weather across the United States remains wide, and the task for decision-makers is less about predicting a single future than about preparing for several, using the best available science to narrow the field while the ocean makes up its mind.
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*This article was researched with the help of AI, with human editors creating the final content.
