How likely is a super
El Niño this winter?
Updated each Monday from the four major ENSO outlooks (NOAA CPC, IRI, BoM, ECMWF SEAS5) and weekly Niño 3.4 observations. Peak season target: DJF 2026-27. Forecast disagreements are surfaced rather than averaged.
Bottom line: 92% chance of at least a moderate El Niño this winter, 25% chance of a 1997 / 2015-magnitude event.
Probabilities are CPC-derived after RONI→trad-ONI translation (live offset +0.50°C, week of 2026-04-22) and a skew-normal fit on CPC's nine-bin strength table. ECMWF SEAS5 ensemble counts are a second cross-check.
Analog tracker
2026-27 trajectory vs reference El Niño events, plus the SEAS5 ensemble forecast (median + uncertainty bands) forward.
Physical state
Current observations vs the same calendar week in past super-event develop years.
| Indicator | Current week of 2026-04-25 | 1997 same week | 2015 same week |
|---|---|---|---|
| Niño 3.4 weekly (traditional) | +0.7°C | −0.1°C | +0.6°C |
| Niño 3.4 weekly (RONI) | +0.2°C | n/a (pre-RONI) | n/a (pre-RONI) |
| 0–300 m heat content anomaly | +1.36°C | +0.7°C | +1.6°C |
| Cumulative westerly wind anomaly since Mar 1 CWWA, ERA5 5°N–5°S, 130°E–150°W, m/s·days | 131 | 289 | 214 |
Impact outlook
Aggregation of institutional impact ranges for the developing event. Probabilities below are from named external sources, conditional on the headline strong-to-super case in section 1 materializing.
Mediterranean
Spain, Portugal, Italy, Greece, southern France. Probability of severe summer 2026 heat and drought: high, >70% Iberia, ~65% Italy/Greece/southern France. The 2024 July Mediterranean heatwave was characterized by World Weather Attribution as "virtually impossible without human-caused climate change". A 2003-magnitude European heat event (~70,000 excess deaths) is rated medium probability (~25-30%) on a strong El Niño compounded with the multi-year Mediterranean drought baseline.
Amazon basin
Probability of major drought 2026: high (>70%); probability of fire season exceeding 2024 hotspot levels: medium-high (~50%). NASA SERVIR characterized the 2023-24 drought magnitude as "roughly double" the 2015-16 event. The 2024 fire season produced a 76% increase in hotspots vs 2023.
Australia and the Great Barrier Reef
Probability of severe bushfire season austral summer 2026-27: high (>65%); GBR mass bleaching: very high (>85%); agricultural drought: high (>70%). The reef has bleached six times since 2016; another super event makes a sixth-in-eight-years bleaching baseline. Australian winter wheat is the cleanest El Niño short on record, with declines of 16% to 46% under prior strong events (1965, 1977, 1982, 1994, 1997, 2023).
Southern Africa
Probability of major drought repeat: ~70% if rains arrive late, per OCHA framing of the 2023-24 baseline ("worst impacts in 40 years"). Probability of a humanitarian appeal exceeding $5 billion: medium-high (~50%). Six SADC countries declared emergency in 2024; back-to-back is the asymmetric humanitarian risk.
India and South Asia
IMD's April 2026 monsoon outlook is 92% of the long-period average, the first below-normal April call since 2015. Of 16 historical El Niño years since 1950, 7 produced below-normal Indian monsoons (IMD MMCFS). Pre-monsoon heat already reached 43.8°C at Akola in mid-April 2026.
United States
California atmospheric river season: above-normal Pacific storm count winter 2026-27 high (~70%), with ~50% probability of a major atmospheric river damage event January-March 2027. Pacific Northwest: warmer-drier winter (~70%) with significant 2026 fire season (~50%). Atlantic hurricane season: high probability (~70%) of below-normal activity from El Niño wind shear, partially offset by warm Atlantic SSTs (2023 produced 20 named storms despite an El Niño base state). Southern Plains drought relief: low-medium (~25-30%); the 2023-24 super event underdelivered there.
Southeast Asia
Significant drought in Indonesia: high (>70%); palm oil production decline: medium-high (~55%). The 2015-16 super event delivered a 13.2% Malaysian palm oil production decline at a 12-month lag. Vietnamese coffee output fell 20% in 2023-24.
Global coral
The 2023-25 fourth global bleaching event already affects ~84% of world reefs (International Coral Reef Initiative, April 2025). Continued mass bleaching across all tropical basins is essentially certain into 2026-27.
Source-by-source check
What each agency said this week, verbatim where useful.
- NOAA CPC strength table, NDJ 2026-27 (RONI)issued 2026-04-09super 25%, strong 26%, moderate 26%, weak El Niño 15%, neutral 8%, La Niña 0%.
- IRI plume, DJF 2026-27issued 2026-04-20El Niño 88%, neutral 11%, La Niña 1%. Strength not broken out in the public Quick Look.
- BoM ENSO Outlookissued 2026-04-28Further warming in the tropical Pacific as models suggest El Niño by late winter. Categorical only.
- ECMWF SEAS5run 2026-04-0151-member SEAS5 ensemble for 2026-10: median Niño 3.4 anomaly +2.21 deg C; 51/51 members above +1.5 (~76% above +2.0, ~25% above +2.5).
Caveats this issue
- The +2.5°C bucket carries a 24–26% range. It comes from a bootstrap that perturbs CPC's published bin probabilities by Gaussian noise (sigma 1 percentage point, matching CPC's whole-percent reporting precision) and refits the skew-normal each time. The range therefore reflects reporting-quantization uncertainty in CPC's table, not underlying forecast uncertainty.
- ECMWF SEAS5 vs CPC, upper tail above +2.5°C trad ONI: SEAS5 has 13/51 members (25%) at 2026-10 (max available lead). CPC's NDJ 2026-27 bucket lands at 24–26%. We subtract SEAS5's own model climatology, which removes its known ENSO warm bias; an observational-climatology subtraction would put SEAS5 higher still. Real disagreement to surface, not a number to average.
- Spring predictability barrier: April–May forecasts at any of these centers carry materially wider error bars than what we'll see in July–August. Treat all numbers as preliminary.