Last week, the US Climate Prediction Center (CPC) maintained a La Nina warning, confirming that cold sea surface temperatures still exist in the equatorial Pacific.
However, the La Nina state is not expected to last long. CPC weather forecasters say La Nina will weaken and end around February 2026.
We have high confidence that a weak La Nina is now at or very close to its peak. The sea temperature in the eastern equatorial Pacific will increase and bring the system to a neutral ENSO state in the next few months, said Nat Johnson, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA).
Currently, La Nina is only at a minimum. The Nino 3.4, NOAA's main measure of the phenomenon, recorded below -0.5 degrees Celsius in early December. This is the lowest threshold to be considered a La Nina phenomenon.
After February 2026, NOAA forecasts that the Pacific Ocean will enter a neutral phase, when not within the conditions of El Nino or La Nina. However, there are signs that a neutral state could shortly exist and that El Nino could return as early as next summer.
During the La Nina phase, trade winds blow from east to west along the equator, pushing warm ocean waters into the western Pacific Ocean, like water being forced to one side in a tilted tank. This is happening in practice.
Over the past several months, an unusually warm ocean of water has been accumulating in the western Pacific Ocean. While the eastern Pacific remains typically La Nina-rich, water temperatures in the west are among the highest since 1950.
This huge thermal power bloc is seen as potential fuel for an El Nino by the end of 2026. Strong but short westerly winds, also known as westerly wind outbreaks, can push warm water back eastward, heating up the entire basin and triggering a rapid reversal to El Nino.
However, having fuel does not mean an El Nino is certain. I think it is still a bit early to say that the current conditions are strong enough to spontaneously start an El Nino, Johnson said.
He said that in the spring of 2014, the Pacific Ocean had many similarities to today. At that time, a large amount of warm ocean waters will also appear in the west and initial westerly winds, raising the forecast of a super El Nino.
But then the easterly winds returned and stopped the El Nino development. The wind did not reverse as expected and El Nino did not happen immediately but was delayed for another year, he said.
If El Nino returns strongly in the summer, the likelihood of hotter-than-average weather around the world by the end of 2026 will increase. Conversely, if the 2014 scenario repeats, the Pacific Ocean could remain neutral for longer and the risk of extreme weather events next year will decrease.
