The world should prepare for extreme weather events as a strong El Niño is set to develop rapidly over the coming months, the United Nations’ weather and climate agency said on Friday.
The World Meteorological Organization (WMO) confirmed the climate phenomenon had already begun and would quickly gain strength between July and September.
El Niño warms surface temperatures in the central and eastern equatorial Pacific Ocean, causing worldwide changes in winds, pressure and rainfall patterns. It typically occurs every two to seven years and lasts around nine to 12 months.
The WMO’s monthly Global Seasonal Climate Update points towards “a rapid development into a strong El Niño event during July-September”. The agency classifies El Niño events as weak, moderate, strong or very strong, meaning the upcoming event is expected to reach the third-highest level.
“El Niño conditions have developed in the tropical Pacific and are forecast to strengthen rapidly over the coming months, increasing the likelihood of extreme weather events in many parts of the world,” the WMO said.
Ocean temperatures rising sharply
Forecasts from global climate centres show a consistent and significant warming of ocean temperatures across the central and eastern equatorial Pacific. Seasonal-average sea-surface temperature anomalies are expected to exceed 2°C in key monitoring regions.
The models show “remarkable agreement, providing high confidence in the outlook”, according to the Geneva-based agency.
El Niño is expected to continue strengthening during the Northern Hemisphere autumn, with its influence extending across many regions of the globe. Meanwhile, the equatorial Atlantic basin is expected to remain generally warmer than average.
The last El Niño contributed to making 2023 the second-hottest year on record and 2024 the all-time high at around 1,55°C above the 1850-1900 pre-industrial average. While El Niño usually peaks between November and February, the resulting spike in temperatures typically comes later.
Drought and heatwave risks increase
WMO chief Celeste Saulo said El Niño conditions were already under way and forecast to strengthen rapidly into a strong event.
“This will intensify the chances of drought and heavy rainfall and the risk of heatwaves on land and marine heatwaves in many regions,” she said.
The agency is stepping up early warning support to help guide preparedness, especially in climate-sensitive sectors like agriculture and health.
“Advanced seasonal forecasts and early warnings are vital to save lives and cushion the impact on our economies and our communities,” Saulo said.
The update predicts an overwhelming likelihood of above-average temperatures across most land areas between 60 degrees south and 60 degrees north, covering nearly all populated areas outside the polar regions.
The July to September rainfall outlook is consistent with a strengthening El Niño, with above-normal rainfall forecast in areas including the southwestern United States, and below normal forecast across the Indian subcontinent and much of Australia.
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Climate change amplifies effects
The WMO says there is no evidence that climate change increases the frequency or intensity of El Niño events. However, the agency believes it can amplify the associated effects, because a warmer ocean and atmosphere increase the availability of energy and moisture for extreme weather events, such as heatwaves and heavy rainfall.
During the northern hemisphere summer, warm waters associated with El Niño can fuel hurricanes in the central and eastern Pacific, while hindering their development in the Atlantic Ocean.
Peru declares emergency
On Thursday, Peru declared a 60-day state of emergency in 800 of its 1 800 municipalities, due to the “imminent danger” of heavy rains linked to El Niño.
More than 9,3 million people in Peru were warned of a very high risk from flooding and landslides.
