2026-27 El Niño Forecast: Potential for Strongest Event on Record

Forecasts Predict Unprecedented El Niño Intensity

Multi-model seasonal forecasts indicate that the 2026-27 El Niño event is likely to be the strongest since reliable records began, potentially exceeding previous records by a significant margin. Data from 667 ensemble members across 14 different seasonal forecast models show a multi-model median peak of 3.6°C for detrended sea surface temperature (SST) anomalies in the Ni±o 3.4 region of the tropical Pacific.

This forecast is notably higher than the previous record of 2.75°C set during the 2015-16 event. The gap between the current forecast median and the previous record is approximately 0.8°C, which is larger than the gap between the strongest and fifth-strongest El Ni
o events of the last 150 years (roughly 0.5°C).

Model Agreement and Probability

There is unusual agreement among the 14 modeling systems used in the forecast. Every model's median peak is categorized as a "super" El Ni
o intensity, and 13 out of 14 models place their median above the 2015-16 record. Only the JAMSTEC SINTEX-F model is an outlier with a median peak of 2.2°C.

Probabilities of a record-breaking event vary slightly depending on the index used:

• Ni±o 3.4 terms: Approximately 91% of ensemble members exceed the 2015-16 record.
• Relative Ni±o 3.4 Index (RONI): Approximately 77% of ensemble members indicate a record event. The RONI index is used to isolate the ENSO signal by subtracting the tropical-mean SST anomaly to avoid conflating El Ni
  o with general ocean warming trends.

Rapid Development and Observed Conditions

The 2026 event is developing faster than the 1997-98 event, which was previously the benchmark for explosive onsets. Unlike the 2015 event, which began in a warm state, the 2026 event launched from conditions resembling La Ni
a in January.

Observed data supports these model projections. As of mid-July, daily SSTs in the Ni±o 3.4 region are already approximately 2°C above their era-adjusted average. No prior year in the 45-year satellite record has been this warm this early, including the benchmark years of 1997 (+1.6°C) and 2015 (+1.3°C).

Impact on Global Temperatures

Because global temperatures typically lag ENSO events by three to five months, the primary warming effect of this event is expected to peak in 2027. This suggests that 2027 could be the warmest year on record by a substantial margin.

There is also a non-trivial chance that late 2026 will be impacted. Current estimates suggest a 28% chance that 2026 will edge out 2024 as the warmest year on record, an increase from 13% at the start of July.

Technical Caveats and Model Skill

While model agreement is high, it is important to note that these models have never been verified in this temperature range. No seasonal forecast system has ever forecast and then verified a 3.6°C El Ni
o because such an event has never occurred. Consequently, while the agreement is reassuring, it does not constitute absolute proof of the outcome.

Community Perspectives and Concerns

Discussion among technical observers highlights concerns regarding the unpredictability of extreme weather events and the potential for infrastructure failure.

"Almost all models underestimated the ocean temperature. We are entering uncharted waters and I fear that at some point we will get an extreme extreme weather event and the worse thing is that we won't see it coming."

Other observers noted the potential for localized impacts, such as increased rainfall in North Texas or extreme heatwaves in Europe, suggesting that these events may necessitate urgent adaptations in home cooling and energy systems.