After months of watching ocean temperatures climb across the tropical Pacific, climate scientists say El Niño is knocking on the door.
As we reported last week, “El Niño is arriving on our doorstep in the coming months with 90 percent certainty,” U.N. Secretary General António Guterres said in a World Meteorological Organization statement.
NOAA Climate Prediction Center’s (CPC) regular monthly update is scheduled for Thursday, June 11. By then, there may be some indices that are getting quite close to El Niño thresholds.
Why hasn’t El Niño been declared already?
The answer comes down to how the phenomenon is defined.
El Niño isn’t based on a single hot week in the Pacific Ocean. Scientists look for sustained warming of sea-surface temperatures in a region of the equatorial Pacific, when sea surface temperatures in the central and eastern equatorial Pacific (known as the Niño-3.4 region) rise at least 0.9 degrees Fahrenheit (0.5 degrees Celsius) above average. The warming anomaly also has to be forecast to persist for five consecutive, overlapping three-month seasons, according to NOAA.
And we are nearly there.
Weekly sea-surface temperature anomalies in the Niño 3.4 region have recently climbed to around 0.5 degrees Celsius above average, right at the threshold commonly associated with El Niño conditions. The challenge is that official classifications rely on longer-term averages rather than short-term spikes.
Just last week, NASA announced that its international sea level satellite observer (Sentinel-6 Michael Freilich) showed seas around Peru were more than 5.9 inches (15 centimeters) higher than long-term averages in mid-May. This is because water expands as it warms, so a rise in sea level indicates increasing temperature. This is another precursor to El Niño developing.
The rapid warming we are seeing in the equatorial Pacific is one reason confidence has increased dramatically in recent months. Earlier this year, forecasters saw only modest odds of El Niño developing. Now, both NOAA and the World Meteorological Organization project an approximately 80% chance that El Niño forms between June and August, with about a 90% chance it persists into late 2026.
Scientists are also paying close attention to the event’s potential strength. While there is still uncertainty about exactly how intense it may become, many forecast models suggest the developing El Niño could reach moderate or even strong levels by late 2026. Some forecasts show this could be the strongest El Niño on record.
If that happens, the impacts could extend far beyond the Pacific. El Niño alters weather patterns around the globe, increasing rainfall in some regions while worsening drought in others. It can also influence hurricane activity, winter storm tracks and global temperatures.
Because human-caused climate change has already warmed the atmosphere and oceans, scientists warn that the effects of a strong El Niño may be amplified.
“The world must treat it as the urgent climate warning it is. El Niño conditions will pour fuel on the fire of a warming world. Impacts will hit even harder, travel even farther, and cross borders with devastating speed,” said Guterres.
For now, the official status remains neutral. But the question is no longer whether conditions are trending toward El Niño, but how quickly the atmosphere catches up with an ocean that is already signaling a major shift is underway.
