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La Niña is projected to return in September 2025 for a brief period.
Despite this, global temperatures are expected to remain above normal due to ongoing greenhouse gas emissions, says WMO.
While La Niña typically cools global temperatures, the persistent warming trend is likely to continue, impacting weather patterns and economic sectors worldwide.
The La Niña phase of the El Niño Southern Oscillation (ENSO) phenomenon in the Equatorial Pacific Ocean may return in September 2025, but global average temperatures will remain above normal, according to the latest update from the World Meteorological Organisation (WMO).
During the La Niña phase of ENSO, sea surface temperatures in the Equatorial Pacific Ocean are lower than average, and this impacts the weather in different parts of the world in different ways. The impacts occur because of changes in atmospheric circulation, especially wind and pressure, and associated rainfall patterns.
Generally, La Niña cools down global average temperatures, but with the background warming due to greenhouse gas emissions, temperatures have remained above normal even during La Niña years.
Neutral ENSO conditions (near-average sea surface temperatures) have been ongoing in the Equatorial Pacific Ocean since March 2025. “There is a 55 per cent chance for sea surface temperatures in the equatorial Pacific to cool to La Niña levels, and a 45 per cent chance for them to remain at ENSO-neutral levels during the upcoming September-November 2025 period,” said the WMO in a press release.
The chances of La Niña conditions prevailing increase to 60 per cent for the October to December period, according to the WMO. The latest ENSO update from the National Oceanic and Atmospheric Administration of the United States stated: “A brief period of La Niña conditions is favoured in the fall and winter of 2025-26 before reverting to ENSO-neutral.”
“Seasonal forecasts for El Niño and La Niña and their associated impacts on our weather are an important climate intelligence tool. They translate into millions of dollars of economic savings for key sectors like agriculture, energy, health and transport, and have saved thousands of lives when used to guide preparedness and response actions,” said Celeste Saulo, secretary-general of the WMO.
“However, naturally occurring climate events such as La Niña and El Niño are taking place in the broader context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather, and impacting seasonal rainfall and temperature patterns,” said the WMO.
This is evidenced by climatic events such as the 2022 early and intense heatwaves in South Asia, which occurred during a La Niña year. In fact, part of the reason for the heatwaves was a north–south pressure pattern related to La Niña. Globally, 2022 was also the fifth or sixth warmest year on record, depending on the dataset used, according to the WMO.
“For September to November, temperatures are expected to be above normal in much of the Northern Hemisphere and large parts of the Southern Hemisphere,” said the WMO. Rainfall predictions resemble conditions typically observed during a moderate La Niña, it added.