A rapidly strengthening El Niño is emerging as a major climate signal for the second half of 2026, with new forecasts suggesting the event could reach exceptionally strong levels later this year and influence weather patterns through the winter of 2026-27.
El Niño, the warm phase of the El Niño Southern Oscillation (ENSO) develops when sea-surface temperatures in the tropical Pacific become unusually warm. The World Meteorological Organization had already indicated a high likelihood of El Niño developing during June-August 2026, while NOAA said in June that the event was expected to strengthen during the autumn.
The latest developments come as several parts of the world are already experiencing unusually active weather, including heavy monsoon rainfall in India and concerns about flooding and extreme rainfall in other regions.
Pacific Ocean warming fuels El Niño
The latest analysis described in the Severe Weather Europe report points to exceptionally strong warming across the tropical Pacific. A major factor behind the rapid development is the combination of strong westerly wind bursts and a large reservoir of warm water beneath the ocean surface.
Westerly winds can push warm water eastward beneath the surface in the form of an oceanic Kelvin wave. As this warm water moves toward the eastern Pacific and rises, it can further increase sea surface temperatures and reinforce the El Niño circulation.
Forecasts cited in the report show the possibility of the event reaching historically high levels during November and December. However, such long range projections remain subject to change as atmospheric and oceanic conditions evolve.
The event is already being closely watched by international weather agencies. NOAA has forecast a high probability of a very strong El Niño during October-December while recent reports have warned that the event could become one of the strongest of recent decades.
Why a strong El Niño matters
A powerful El Niño can reorganise atmospheric circulation far beyond the Pacific Ocean. Changes in the Walker circulation and jet streams can affect rainfall, temperature and storm tracks across North America, South America, Asia, Australia and other regions.
The exact consequences, however, differ from one El Niño to another. Scientists therefore caution against treating a seasonal forecast as a prediction of specific storms or floods months in advance.
One recent analysis comparing the 2014-16 and 2023-24 El Niño events found that both produced substantial increases in global mean sea level, largely because changes in rainfall and terrestrial water storage transferred additional water from land into the oceans. The study estimated increases of 9.16 mm and 7.70 mm respectively during the development phases of the two events.
A strong 2026 El Niño could similarly influence global temperatures and sea levels, although the magnitude of any effect will depend on regional rainfall, runoff, ocean temperatures and other climate factors.
India faces another spell of heavy monsoon rain
The developing El Niño comes as India is experiencing an active monsoon season, with several states facing heavy and very heavy rainfall.
The India Meteorological Department has forecast heavy rainfall across parts of northern, central and eastern India, including areas of Rajasthan, Haryana, Delhi, Punjab, Himachal Pradesh, Jammu and Kashmir, Uttar Pradesh, Madhya Pradesh, Gujarat and Odisha. East Rajasthan has been identified as a particularly vulnerable region for intense rainfall.
A fresh low pressure system is also expected to support another widespread spell of rain over parts of India from Thursday, August 13.
The continuing rainfall has raised concerns about flooding waterlogging and landslides, particularly in mountainous areas.
Climate change adds to Himalayan disaster risk
The extreme rainfall concerns are particularly significant in the Himalayas. The Centre recently told the Lok Sabha that climate change has increased the intensity and frequency of extreme rainfall events in the Himalayan region.
The government has constituted a Multi Sectoral Central Team to investigate the increasing occurrence of cloudbursts, flash floods, landslides and extreme rainfall in Himachal Pradesh. The team includes experts from agencies including the National Disaster Management Authority, Central Building Research Institute, Indian Institute of Tropical Meteorology, IIT Indore and other organisations.
The assessment also highlighted accelerated snowmelt and instability of glacial moraines as factors that can increase runoff and slope failure risks in high altitude areas.
This combination is particularly dangerous because intense rainfall falling on already saturated or unstable mountain terrain can rapidly trigger flash floods, landslides and debris flows.
El Niño could reshape weather in North America
The strongest effects of the developing El Niño are expected to become clearer during autumn and winter in North America.
Long-range forecasts cited by Severe Weather Europe indicate the possibility of an amplified winter circulation pattern, with an active southern jet stream and significant differences between northern and southern parts of the United States.
Such a pattern can favour warmer conditions across parts of Canada and the northern United States while increasing the potential for storms, rainfall and periods of colder weather farther south and east.
Recent climate scientists assessments have also warned that a strong El Niño could bring wetter conditions and increased flooding risks to parts of the western and southeastern United States. California, in particular, could experience periods of heavy rainfall that may worsen coastal flooding and erosion.
Europe could see a milder, wetter winter
The long range projections also indicate a predominantly westerly atmospheric flow across Europe during winter 2026-27.
Such a setup could bring relatively mild and moist Atlantic air to large parts of the continent. However, individual cold-air outbreaks and storms remain possible, particularly across northern and northeastern Europe and higher elevations.
Because these forecasts cover several months, scientists stress that they describe broad seasonal tendencies rather than precise weather events.
El Niño and rising global temperatures
The developing El Niño is also important because it is occurring against a backdrop of already elevated global temperatures.
El Niño tends to raise global average temperatures because additional heat is transferred from the tropical Pacific Ocean into the atmosphere. A particularly strong event could therefore contribute to exceptionally warm global conditions in late 2026 or early 2027.
The combination of natural climate variability and human driven warming is especially significant for extreme weather. Climate change does not cause every individual storm or rainfall event, but warmer atmospheric and oceanic conditions can alter the intensity, frequency or consequences of some extremes.
Scientists urge caution over record strength forecasts
Despite the dramatic projections, it is too early to say with certainty that the 2026 event will become the strongest El Niño ever recorded.
Seasonal models become less reliable the farther into the future they project, and El Niño intensity can change rapidly depending on future wind bursts, ocean heat content and atmospheric feedbacks.
The current evidence nevertheless indicates that the tropical Pacific is undergoing an unusually strong warming episode. NOAA and other international agencies are monitoring the event closely, while meteorological services are assessing its potential consequences for the coming months. ([NOAA][5])
The significance of the developing event extends beyond the Pacific. From India’s intense monsoon rainfall and Himalayan landslide risks to potential flooding in North America and changing winter conditions in Europe, the coming months could provide a striking example of how a change in one part of the global climate system can influence weather thousands of kilometres away.
For now, the key message from scientists is not that every extreme weather event is being caused by El Niño, but that a rapidly strengthening El Niño combined with a warmer global climate could increase the potential for significant weather disruptions in several regions during late 2026 and early 2027.