The World Meteorological Organization (WMO) has warned that the El Nino climate pattern is taking shape and is likely to produce widespread extreme weather later this year. Forecasts cited by the WMO indicate an 80% probability that the event will develop between June and August, and a 90% probability that it will continue until at least November.
El Nino is a naturally recurring ocean-atmosphere phenomenon that appears every two to seven years. It is driven by a weakening of the trade winds, which allows sea surface temperatures in the eastern Pacific to rise. Those warmer waters typically push global temperatures higher and disrupt established rainfall patterns - producing drought in some areas, heavy precipitation in others - and altering hurricane and cyclone behaviour.
Two factors make the current outlook especially concerning, experts say. First, there remains a material possibility that the coming El Nino could be stronger than average. The WMO notes that model runs differ - some point to a strong event, others do not - but its ensemble forecasts include scenarios in which sea surface temperatures in the eastern Pacific rise by at least 1.5 degrees Celsius above average, a conventional threshold for designating a strong El Nino.
Second, and perhaps more consequential, is the elevated baseline in which this El Nino will occur. Greenhouse gas emissions have increased the planet’s average temperature by roughly 1.3 degrees Celsius since pre-industrial times. That warmer baseline does not simply add a constant increment of heat; it amplifies the extremes produced by El Nino, making temperature spikes hotter and precipitation anomalies - both deficits and excesses - more intense.
"When we get an El Nino, because of the underlying climate change ... these things become more intensified and they’re more impactful," said Piers Forster, Professor of Physical Climate Change at the University of Leeds. The WMO has pointed to the combined effect of El Nino and long-term warming as a reason it could produce record-setting global temperatures, warning that 2027 could become the hottest year since records began. The organisation also notes that the last El Nino year, 2024, currently holds the global temperature record for an El Nino year and was regarded as a strong event.
El Nino’s influence is uneven geographically. Typical patterns include increased rainfall across parts of southern South America and sections of Central Asia, while regions such as Central America and Australia often experience drier conditions. The phenomenon also tends to intensify heatwaves, including in places remote from the tropical Pacific such as Europe. Those weather shifts carry direct consequences for food production, industry operations and human safety.
Recent extreme weather offers an example of how the two factors - a strong El Nino and background warming - can interact. In April and May 2024 severe floods in Rio Grande do Sul in Brazil resulted in more than 180 fatalities and displaced about 600,000 people. Climate scientists involved in studying the event concluded that both El Nino and climate change heightened the rains that generated the catastrophe. Francisco Aquino, who heads the University of Rio Grande do Sul’s climate centre, warned that a strong El Nino this year could produce a comparable scenario. "When you have an El Nino over what climate change already brought, the risks are enormous," he said. "A strong El Nino can lead to the exact same scenario we saw then, because the world keeps getting warmer, and the temperature in the ocean keeps rising."
Another region where the combined effect is felt acutely is southern Africa. There, El Nino tends to reduce rainfall during the main rainy season, an outcome that limits hydropower generation and depresses crop yields. Izidine Pinto, a senior climate researcher at the Netherlands Meteorological Institute, noted that climate change will make those below-normal rainfall periods more severe - either by extending their duration or by reducing the total rainfall - and that farmers reliant on rain-fed agriculture are particularly vulnerable.
Beyond rainfall and temperature, changes to the thermal energy in the Pacific also alter the environment for tropical cyclone formation. Antonio Navarra, head of Italy’s Euro-Mediterranean Center on Climate Change, cautioned that warmer Pacific waters create a more favourable setting for stronger cyclones. "Because the water in the Pacific will be much warmer, there will be a much more favourable environment for the formation of tropical cyclones.... El Nino will input an enormous amount of energy into the system, so everything will be more intense," he said.
For some researchers, the danger goes beyond the immediate impacts this year. They argue that a strong El Nino interacting with ongoing warming offers a preview of climate conditions that could become routine within a few years - potentially as soon as around five years from now - even in years without an El Nino. "It does give a window into the future," Forster said.
Theodore Keeping, a research associate at Imperial College London, emphasised that El Nino exerts a distinct influence on atmospheric circulation that is not identical to the effects of gradual warming. Nonetheless, he said, the pattern can reveal weather circumstances that, in a warmer climate, would otherwise be found only on rarer occasions. "You’re able to kind of sample weather conditions that you would otherwise in a neutral El Nino (year) only expect to see in a warmer climate," he commented.
Each El Nino is unique, and the precise mix of regional impacts will vary. Forecast uncertainty remains, and that uncertainty is itself a source of risk for sectors that depend on stable weather patterns. Agriculture, energy systems that rely on hydropower, and industries sensitive to extreme weather - including supply chains and insurance markets - are among those the WMO specifically highlights as vulnerable to the combined effects of El Nino and climate change.
With some climate models projecting a strong event and with the global temperature baseline already elevated, meteorological agencies and governments face a narrow window to plan for the spectrum of possible impacts - from heatwaves and reduced reservoir inflows to heavier rains and stronger Pacific storms. The WMO’s probabilities make the risk tangible: a likely El Nino that could last through the end of the year and interact with long-term warming to produce intensified extremes.
Summary: The WMO sees an 80% chance of El Nino forming between June and August and a 90% chance it will last into November. Some models indicate the event could be strong, defined by eastern Pacific sea surface temperatures rising at least 1.5C above average. Climate change - which has warmed the planet by about 1.3C since pre-industrial times - will amplify El Nino’s impacts, increasing the likelihood of intense heatwaves, droughts, floods and stronger cyclones, with significant implications for agriculture, hydropower and disaster risk.