WASHINGTON — Climate experts are warning that El Niño is strengthening rapidly and could become one of the most powerful events on record by late 2026, increasing the likelihood of higher global temperatures and major shifts in rainfall patterns around the world.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center said in its Aug. 13 outlook that El Niño is strengthening, with a greater than 90% chance of a very strong event during Northern Hemisphere fall and winter 2026-27.
The agency’s forecast also assigns a 69% chance that the October-December period could reach “historic” strength, defined as a three-month Relative Oceanic Niño Index, or RONI, of at least 2.5 degrees Celsius above normal. That would exceed the strength of previous El Niño events in records dating to 1950.
The World Meteorological Organization has reached a similar conclusion. Its latest global seasonal update says a strong El Niño is expected to intensify during August through October, increasing the likelihood of above-normal temperatures across much of the world and altering seasonal rainfall patterns.
The forecasts do not mean every region will experience the same weather or that every expected impact is certain. El Niño shifts the odds; it does not dictate the weather on a particular day in a particular city.
But the projected scale of the event matters. A very strong El Niño layered on top of human-caused global warming and unusually warm oceans could amplify heat, influence storm tracks, alter drought and flood risks, and put additional pressure on food systems, water supplies, coral reefs and public health.
What El Niño is
El Niño is the warm phase of the El Niño-Southern Oscillation, known as ENSO, a naturally occurring climate pattern centered in the tropical Pacific Ocean.
During El Niño, sea-surface temperatures in the central and eastern equatorial Pacific become warmer than average. That added ocean heat changes atmospheric circulation, the large-scale movement of air that helps shape weather patterns far beyond the Pacific.
In a typical El Niño event, warmer tropical Pacific waters affect trade winds, rainfall over the ocean, and the position of the jet stream. Those changes can affect temperature and rainfall patterns throughout North America, South America, Africa, Asia, Australia and beyond.
The opposite ENSO phase is La Niña, when sea-surface temperatures in the same region become cooler than average. Neutral conditions fall between the two.
Scientists track ENSO using several measurements, including sea-surface temperatures, wind patterns, rainfall, cloudiness, and changes in atmospheric pressure. NOAA’s current forecast uses the Relative Oceanic Niño Index, a measure designed to account for the background warming of the global ocean when assessing El Niño strength.
That adjustment is important. The planet is warmer than it was decades ago, so scientists need tools that distinguish an El Niño event from the broader long-term rise in ocean temperatures caused by climate change.
Why this forecast is unusual
NOAA’s forecast is notable not merely because El Niño is present, but because of the projected intensity.
The Climate Prediction Center says there is more than a 90% chance of a very strong El Niño during the fall and winter of 2026-27.
A very strong El Niño can produce more pronounced shifts in global weather patterns than a weaker event. The agency’s October-December forecast gives a 69% chance of a historic event exceeding a RONI value of 2.5 degrees Celsius.
The World Meteorological Organization’s multi-model forecast is also projecting large sea-surface temperature anomalies. It expects the seasonal average in key monitoring regions to reach about 2.9 degrees Celsius above normal during August-October, with intensification expected to peak around November.
That level of agreement among models increases forecasters’ confidence. WMO said the spread among forecast systems is narrow, meaning many different models are pointing toward a similar result.
Forecast confidence is higher now than it would be earlier in the year because the climate system has moved beyond the period scientists call the “spring predictability barrier.” ENSO forecasts made during Northern Hemisphere Spring are often less reliable because conditions in the Pacific are changing quickly. By late summer, ocean and atmospheric signals are usually clearer.
Still, prediction is not certainty. The exact peak strength, duration, and regional effects can change. Other climate patterns, including the Indian Ocean Dipole, the Atlantic Ocean’s temperature patterns, Arctic conditions and short-term atmospheric variability, can influence how El Niño plays out in specific places.
Global heat is the clearest risk
The most consistent global effect of El Niño is additional warming.
A strong El Niño tends to raise global average surface temperatures because heat stored in the tropical Pacific is released into the atmosphere. The global temperature impact often becomes most visible several months after the ocean warming strengthens.
WMO says above-normal temperatures are expected across much of the world during the August-October period.
That forecast comes as global temperatures are already elevated because of greenhouse-gas emissions from burning fossil fuels, deforestation, and other human activities. Climate change has raised the baseline. El Niño can add a temporary but substantial boost on top of that trend.
The combination can have serious consequences.
Extreme heat increases health risks, especially for older adults, infants, outdoor workers, people without air conditioning and those with chronic medical conditions. High temperatures can strain electricity grids, reduce crop yields, worsen drought, and increase wildfire danger.
Heat also affects water. Hotter conditions increase evaporation from soils, reservoirs and rivers, making dry areas drier, and increasing the intensity of heavy rainfall when moisture-laden storms form.
Climate scientists stress that El Niño does not cause climate change. It is a natural pattern. But its effects occur in a warmer world, meaning the heat and moisture it helps redistribute can produce more damaging outcomes than similar events would have produced decades ago.
Rainfall changes: floods in some places, drought in others
El Niño does not create one universal weather outcome. Its most important effect is to shift rainfall patterns.
Some areas may even see above normal rainfall, increasing the threat of flooding and landslides. Others may receive less rain, worsening drought, wildfire risk, and water shortages.
The World Meteorological Organization said the developing El Niño is likely to produce significant shifts in rainfall, with wetter conditions expected in some regions and greater drought risk in others.
In the United States, El Niño often influences winter weather, especially across the southern tier. Historically, stronger El Niño events have been associated with wetter-than-average conditions in parts of the southern United States and a tendency toward milder conditions in parts of the northern tier.
But “often” is not “always.” A strong El Niño can influence probabilities, but local outcomes depend on many factors. A state may experience a wet season overall while still receiving rain in a few destructive storms rather than evenly distributed precipitation.
For California and parts of the Southwest, El Niño years can increase the chance of significant winter precipitation. That may benefit water supplies after drought, but it can also increase risks of flash flooding, debris flows and coastal erosion, particularly in areas recently affected by wildfire.
Across the Pacific Northwest and parts of the northern United States, El Niño can bring warmer winter conditions and reduced mountain snowpack. That can affect ski seasons, river flows, and water availability during the following spring and summer.
In other parts of the world, the effects can be more severe. El Niño is often linked to drought risks in Australia, Indonesia and parts of southern Africa, while parts of East Africa and the west coast of South America may face increased rainfall and flooding.
The exact regional map varies from event to event. That is why national and local weather agencies issue more detailed seasonal forecasts rather than relying only on a global El Niño label.
The Indian Ocean could amplify impacts
Climate experts are also watching the Indian Ocean.
WMO said a positive Indian Ocean Dipole, or IOD, is forecast to develop alongside El Niño. A positive IOD occurs when the western Indian Ocean becomes warmer than average while waters near Indonesia become cooler than average.
That pattern can reinforce dryness in Indonesia and parts of Australia while contributing to wetter conditions in parts of East Africa.
When El Niño and a positive IOD occur at the same time, their effects can interact. In regions already vulnerable to drought or flooding, the combination may increase the likelihood of extreme seasonal conditions.
WMO also expects tropical Atlantic sea-surface temperatures to remain above normal. Warm Atlantic waters can affect hurricane activity, rainfall and heat patterns, though the final outcome depends on several interacting conditions.
The presence of multiple warm-ocean patterns is one reason scientists are emphasizing preparation rather than treating El Niño as a distant or abstract phenomenon.
Risks for agriculture, water and coral reefs
The consequences of a strong El Niño can extend well beyond weather forecasts.
Agriculture is particularly vulnerable because crops depend on predictable rainfall and temperature patterns. Drought can reduce harvests and increase food prices, while floods can destroy crops, damage roads, and limit access to markets.
In regions dependent on rain-fed farming, a failed seasonal rainfall pattern can threaten food security. Governments and aid organizations use El Niño forecasts to pre-position food assistance, protect water supplies, and advise farmers on planting decisions.
Water managers also watch ENSO forecasts closely. Reservoir operations, irrigation planning, flood-control measures, and hydropower generation can all be affected by expected changes in rainfall and snowpack.
Coral reefs face another major risk. Warmer ocean temperatures can trigger coral bleaching, a stress response in which corals expel the algae that provide much of their color and energy. Severe or prolonged bleaching can kill reefs and damage fisheries, tourism and coastal protection.
NOAA’s Coral Reef Watch said the current El Niño is strengthening and noted the high probability of a very strong event during the coming Northern Hemisphere fall and winter.
The world’s reefs have already faced repeated heat stress in recent years. Another strong ocean-warming event could worsen pressure on ecosystems that are vital to many coastal communities.
What forecasts can, and cannot, say
Seasonal climate forecasts are different from daily weather forecasts.
A daily forecast might say there is a 70% chance of rain tomorrow. An El Niño outlook says that, over a three-month period, the probability of wetter, drier, hotter or cooler conditions is shifted relative to what is normal for that season.
That distinction matters.
A strong El Niño can increase the odds of a wet winter in one region, but it cannot predict the exact dates of storms, the amount of rain in a particular neighborhood or whether a single flood will occur.
Similarly, a forecast for above-normal temperatures does not mean every day will be hot. It means the seasonal average is more likely to be warmer than the historical average.
People should therefore avoid two common mistakes: assuming El Niño guarantees a specific local outcome and dismissing the forecast because one day’s weather does not match the pattern.
The best use of climate predictions is risk management. Communities, businesses and households can use outlooks to review flood plans, manage water, prepare for heat, protect crops, and ensure that emergency systems are ready.
Preparing for a stronger El Niño
Officials and residents can take practical steps as the event develops.
- Local governments can examine flood-control infrastructure, emergency communication plans and heat-response programs.
- Water agencies can revise drought and reservoir management plans.
- Farmers can receive advice from agricultural-extension services on crop timing, irrigation and drought-resistant practices.
- Health agencies can expect heat-related illness and disease risks that may travel with rain and temperature.
- Coastal communities can track coral-bleaching alerts, high-surf forecasts and erosion risks.
- Households in flood-prone areas can review insurance, clear drainage routes, and follow local emergency alerts.
For the United States, the most relevant period will be the coming fall and winter. NOAA’s forecast suggests the strongest conditions are likely during that window, although El Niño is expected to persist into Northern Hemisphere Spring 2027.
The forecast does not guarantee disaster. It offers time to prepare.
El Niño is a recurring feature of the climate system, but its effects are arriving in a world that is already warmer, more populous and more interconnected. That means a powerful event can turn existing vulnerabilities, weak infrastructure, drought, food insecurity, coastal exposure and public-health strain, into more serious crises.
The message from climate experts is not that every forecast will come true exactly as predicted. It is that the odds of disruptive global weather have risen sharply, and that governments, businesses and communities should act while there is still time.