Is this the strongest El Niño ever recorded? As of Thursday, the honest answer from US forecasters is: not yet, officially, and probably soon. On Oct. 8 the National Oceanic and Atmospheric Administration's Climate Prediction Center raised the odds that this autumn's event will exceed every El Niño since 1950 to 83%. Whether it already counts as a record, though, depends on the ruler you use.

What NOAA and WMO Said on Oct. 8

The Climate Prediction Center kept its El Niño Advisory in place and said the event strengthened further in September, according to a summary by The Watchers. Its relative sea surface temperature indices rose to +2.1°C in the Niño-3.4 region, +3.0°C in Niño-3 and +3.9°C in Niño-1+2. Anomalies exceeded +4°C in parts of the eastern equatorial Pacific, and temperatures at depth were more than 10°C (18°F) above average.

The center gave an 83% chance that the three-month relative Oceanic Niño Index for October to December reaches at least +2.5°C, a level that would exceed all earlier events in its record, which starts in 1950. That is up from 75% in September. The same summary reports 54% for September to November and 70% for November to January.

The World Meteorological Organization issued a separate outlook the same day. Its multi-model forecast, drawn from 13 climate centers, put the October-December Niño-3.4 anomaly near +3.7°C, peaking around December, and said El Niño is almost certain to persist through February 2027. The two figures are not interchangeable because they use different baselines and methods.

Two Rulers, Two Answers

The record question comes down to measurement. The traditional Oceanic Niño Index compares the Pacific with a fixed historical average. By daily readings, the central and eastern Pacific reached 3.08°C above the 1991-2020 average on Sept. 21, warmer than any El Niño on record, Science News reported on Sept. 24. The Washington Post likewise reports that the central equatorial Pacific has surged more than 3.4°C above average, topping the November 2015 record.

NOAA does not use that yardstick as its official measure. Since February 2026 it has used the Relative Oceanic Niño Index, which subtracts the background warming of the whole tropical ocean to show how much hotter the El Niño region is than its surroundings. That index tracks the event's power to shift weather around the world more closely. By that measure, the 2026 event is not at record levels yet. Science News says the 1997-98 event still tops it, and another report ranks it third, behind 1982-83 as well.

My view: the argument over the index is real science, not hair-splitting, but it can distract from the part everyone agrees on. Every major forecaster expects it to keep strengthening into December.

The Warming Backdrop

El Niño is arriving on an already hot planet. The Copernicus Climate Change Service reported that August 2026 was the warmest August on record, above 2023 and 2024, and the Met Office called it the joint warmest month ever recorded, with temperatures above 1.5°C over pre-industrial levels. Global sea surface temperatures also hit records.

Science News notes there is no scientific consensus yet on how much climate change shapes El Niño strength, though some models suggest more greenhouse gas leads to more extreme swings. The question has a cousin in Blogerroom's report on a study finding warming is breaking a 400-year link between the Indian and Pacific oceans, a reminder that the ocean patterns scientists once treated as fixed are shifting.

Where It Is Already Biting

The atmosphere is responding. NOAA reported enhanced rainfall over the central and eastern Pacific while convection remained suppressed over Indonesia, the pattern that dries the western Pacific and feeds fires. That is the backdrop to the Indonesian wildfire season that Blogerroom covered, which officials warn may last into November.

WMO's three-month outlook favors wetter-than-normal conditions across the central and eastern equatorial Pacific, the Greater Horn of Africa, parts of Central Asia and coastal East Asia, and southeastern South America. It favors drier conditions over the Indian subcontinent, southern Central America, parts of the Caribbean and northwestern South America. Both agencies caution that a stronger El Niño raises the odds of these patterns without guaranteeing them for any one place.

Why 2027 Matters

The bigger consequence may come next year. Carbon Brief reported in September that scientists have projected a very strong El Niño could push global temperatures to a new record, and global air temperatures typically lag the Pacific by a few months.

The practical lesson is about timing. Impacts begin before the peak: drought stress, fire seasons and crop risks are already in motion, while the largest effects on global temperature usually follow in the months after the peak.

What to Watch Next

NOAA issues its seasonal outlook on Oct. 15, which will show how the forecast translates into temperature and rainfall odds for the winter. The next ENSO discussion in November will show whether the relative index finally crosses into record territory. And the Copernicus bulletin for September, due shortly, will show whether the ocean heat is lifting global air temperatures further.

If the 83% forecast verifies, 2026 will earn the label forecasters have been reluctant to use. Whatever the name, the effects of the strongest event in decades will be felt well into next year.