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Fenrir Research · Yggdrasil Ledger · Climate & Markets Series · Part III

The 2026–27 El Niño:
What Has Changed and What It Means

A standalone update on signal strength, probability shifts,
and scenario implications — as of April 22, 2026.

El Niño Watch · Probability Shifts · ECMWF Ensemble · Scenario Analysis · Portfolio Positioning

“The spring predictability barrier means these numbers will sharpen once June data is in, but the direction of travel is unambiguous.”

— Fenrir Research, April 2026

Since the Part II Markets & Portfolio report was written, the ENSO signal has strengthened materially. This update tracks the probability evolution, key forecast shifts, and what the developing El Niño means for markets.

Fenrir Research, a division of Yggdrasil Ledger

← Read Part II: Impact and Positioning

Since the Part II Markets & Portfolio report was written, the ENSO signal has strengthened materially. The April 9 NOAA Advisory put El Niño probability at 61% for May–July 2026. By April 19, the IRI mid-month update upgraded that to 70% for April–June 2026, with El Niño remaining dominant at 88–94% probability through the rest of 2026. The ECMWF ensemble — which draws on the most recent subsurface ocean data — is now projecting anomalies that would qualify as Super El Niño territory for roughly half of its ensemble members by October. The spring predictability barrier means these numbers will sharpen once June data is in, but the direction of travel is unambiguous.

Current ENSO Status — April 22, 2026 ENSO-Neutral, rapidly transitioning. Final La Niña Advisory issued April 9. El Niño Watch in effect. IRI mid-April update: 70% probability El Niño already developing in AMJ 2026, rising to 88–94% through end-2026. ECMWF April ensemble: ~50% of members project NINO3.4 ≥ +2.5°C by October — Super El Niño threshold. NOAA official: 33% chance of a strong event (≥+1.5°C) by October–December. The spread between institutions reflects spring predictability barrier uncertainty, not a fundamental disagreement about ocean state.
Tracker

Shifting Probability by Forecast Date

The table below tracks the evolving probability of El Niño development and intensity across successive forecast releases. It will be updated each month as new NOAA, IRI, and ECMWF data is published. The direction is clear — both the likelihood of the event forming and the probability of a strong-to-super event have risen at every successive update.

El Niño 2026 Probability Tracker — Updated Monthly · Source: NOAA CPC / IRI / ECMWF

Forecast Date Source Any El Niño Strong ≥+1.5°C Super ≥+2.0°C Target Window Move
March 2026 NOAA CPC
62%
17%		 — Jun–Aug 2026 Baseline
April 9, 2026 NOAA CPC
61%
33%
~13%		 May–Jul 2026 ↑ +16pts strong
April 19, 2026 IRI / Columbia
70%
~40%
~20%		 Apr–Jun 2026 ↑↑ +9pts total
April 2026 ECMWF C3S
~98%
~80%
20–25%		 Sep–Dec 2026 ↑↑↑ Most bullish
May 2026 NOAA CPC Update pending — post this month’s release
Jun 2026 NOAA CPC Post spring barrier — forecast confidence increases sharply

ECMWF uses 1981–2010 baseline vs NOAA’s 1991–2020 — tendency to inflate anomaly estimates slightly. June 2026 post-barrier forecast is the key resolution point for intensity. This table is updated monthly.

The Spring Predictability Barrier Forecasts issued before June carry elevated uncertainty — the tropical Pacific atmosphere and ocean are at their most decoupled in boreal spring, and models frequently diverge during this window. The spread between NOAA (33% strong) and ECMWF (80% strong) reflects this rather than disagreement about the physical state of the Pacific. The subsurface ocean heat signal — which provides 4-month lead time on surface conditions — already confirms an El Niño will develop. The June forecast will be significantly more reliable for intensity.
NOAA ONI Record · RONI Comparison

ENSO Phase History: 2001–2026

The colour-coded grids below show the ENSO phase record from 2001 to early 2026 using two different indices. Both display 3-month running mean SST anomalies in the NINO3.4 region — the difference is in the baseline each uses to compute the anomaly.

ONI — Oceanic Niño Index

NOAA’s official ENSO classification index. Anomalies are computed against a fixed, periodically updated 30-year climatology (currently 1991–2020). This is the standard used to formally declare El Niño and La Niña events, making it the reference for historical comparisons and cross-source verification.

RONI — Relative ONI

NOAA’s Relative Oceanic Niño Index — the same 1991–2020 base period as ONI, but computed from relative SST anomalies: the average tropical mean (20°N–20°S) SST is subtracted from the Niño 3.4 anomaly, removing the global warming trend signal. This isolates the true ENSO-driven forcing from background ocean warming, making it a more physically meaningful measure of El Niño/La Niña strength. NOAA CPC now uses RONI as its operational definition for El Niño and La Niña episodes.

In practice, RONI values differ from ONI because they subtract the tropical mean SST warming signal. This means RONI is generally lower than ONI in recent decades — events that appear stronger on ONI may be weaker on RONI, since some of the apparent anomaly is attributable to global warming rather than ENSO dynamics. For the 2026–27 cycle, RONI provides the cleaner read on true El Niño forcing strength.

El Niño Weak +0.5–+0.9°C
Moderate +1.0–+1.4°C
Strong +1.5–+1.9°C
Super ≥+2.0°C
La Niña Weak −0.5–−0.9°C
Moderate −1.0–−1.4°C
Strong ≤−1.5°C
Neutral −0.5 to +0.5°C
ONI · Fixed Baseline (1991–2020)
Year DJFJFMFMAMAM AMJMJJJJAJAS ASOSONONDNDJ
2001-0.7-0.5-0.4-0.3-0.2-0.10.00.0-0.1-0.2-0.3-0.3
20020.0+0.1+0.2+0.4+0.7+0.9+0.9+1.0+1.1+1.3+1.4+1.2
2003+1.1+0.8+0.40.0-0.1-0.1+0.2+0.4+0.4+0.4+0.4+0.4
2004+0.4+0.3+0.2+0.2+0.3+0.4+0.6+0.7+0.8+0.7+0.7+0.7
2005+0.6+0.5+0.4+0.4+0.4+0.3+0.2+0.10.0-0.1-0.5-0.8
2006-0.9-0.8-0.6-0.4-0.20.0+0.1+0.3+0.5+0.8+1.0+1.1
2007+0.8+0.4+0.1-0.1-0.1-0.1-0.3-0.5-0.8-1.1-1.2-1.4
2008-1.4-1.3-1.1-0.8-0.6-0.4-0.20.0+0.1+0.1+0.20.0
2009-0.10.0+0.1+0.2+0.3+0.5+0.6+0.6+0.8+1.0+1.4+1.6
2010+1.5+1.2+0.8+0.40.0-0.3-0.7-1.0-1.3-1.5-1.6-1.6
2011-1.5-1.3-1.1-0.8-0.5-0.3-0.3-0.5-0.8-1.0-1.1-1.0
2012-0.9-0.7-0.5-0.3-0.1+0.1+0.3+0.3+0.3+0.3+0.1-0.2
2013-0.4-0.3-0.20.00.0-0.1-0.2-0.3-0.4-0.3-0.20.0
2014+0.1+0.1+0.1+0.2+0.3+0.2+0.2+0.3+0.5+0.6+0.7+0.7
2015+0.6+0.7+0.9+1.1+1.2+1.4+1.6+1.9+2.1+2.4+2.5+2.5
2016+2.2+1.8+1.4+0.9+0.5+0.1-0.2-0.5-0.7-0.7-0.7-0.7
2017-0.4-0.3-0.1+0.1+0.3+0.3+0.20.0-0.1-0.4-0.7-1.0
2018-0.9-0.8-0.6-0.4-0.1+0.2+0.5+0.8+0.9+1.0+0.9+0.8
2019+0.8+0.8+0.8+0.8+0.7+0.6+0.4+0.3+0.2+0.3+0.5+0.5
2020+0.5+0.5+0.4+0.3+0.1-0.1-0.3-0.6-0.9-1.2-1.3-1.3
2021-1.2-1.1-0.9-0.7-0.6-0.6-0.5-0.6-0.8-0.9-0.9-1.0
2022-1.0-1.0-1.0-1.0-1.0-1.0-0.9-1.0-1.1-1.3-1.4-1.4
2023-1.1-0.8-0.5-0.1+0.4+0.9+1.1+1.4+1.6+1.9+2.0+2.0
2024+1.9+1.5+1.1+0.5+0.1-0.1-0.1-0.2-0.3-0.5-0.7-0.8
2025-0.9-0.8-0.7-0.5-0.2-0.10.0+0.1+0.10.0-0.1-0.2
2026-0.2-0.1+0.1·········

Source: NOAA CPC ONI v5. 2026 cells shown for completed seasons only (· = not yet available).

RONI · Relative SST Anomalies (1991–2020 base)
Year DJFJFMFMAMAM AMJMJJJJAJAS ASOSONONDNDJ
2001-0.6-0.5-0.5-0.5-0.3-0.10.00.00.0-0.2-0.2-0.3
2002-0.10.00.0+0.1+0.4+0.7+0.9+1.1+1.3+1.4+1.5+1.2
2003+0.9+0.5+0.2-0.2-0.4-0.30.0+0.2+0.2+0.2+0.3+0.3
2004+0.3+0.1+0.1+0.2+0.3+0.5+0.7+0.8+0.9+0.8+0.7+0.7
2005+0.6+0.4+0.3+0.3+0.20.0-0.1-0.10.0-0.2-0.5-0.8
2006-0.9-0.9-0.6-0.4-0.10.0+0.1+0.3+0.5+0.8+0.9+0.9
2007+0.6+0.2-0.2-0.4-0.4-0.5-0.6-0.8-1.0-1.3-1.4-1.5
2008-1.6-1.5-1.3-0.9-0.8-0.5-0.3-0.2-0.3-0.4-0.6-0.8
2009-0.9-0.8-0.7-0.4-0.1+0.1+0.3+0.4+0.6+0.9+1.3+1.6
2010+1.5+1.1+0.6+0.1-0.5-1.0-1.3-1.5-1.7-1.7-1.7-1.6
2011-1.4-1.2-0.9-0.7-0.5-0.3-0.4-0.5-0.7-0.9-1.0-1.0
2012-0.8-0.6-0.6-0.5-0.30.0+0.3+0.4+0.4+0.2-0.1-0.4
2013-0.6-0.6-0.5-0.4-0.4-0.4-0.4-0.3-0.3-0.2-0.2-0.3
2014-0.5-0.5-0.30.0+0.10.0-0.1-0.1+0.1+0.4+0.5+0.6
2015+0.5+0.4+0.5+0.6+0.8+1.0+1.3+1.6+1.9+2.2+2.3+2.4
2016+2.2+1.8+1.3+0.5-0.1-0.6-0.9-1.0-1.1-1.1-1.1-1.0
2017-0.7-0.5-0.3-0.1+0.1+0.1-0.2-0.5-0.7-1.0-1.1-1.3
2018-1.1-1.0-0.9-0.7-0.30.0+0.1+0.2+0.4+0.7+0.8+0.7
2019+0.6+0.6+0.6+0.5+0.3+0.20.0-0.10.0+0.1+0.2+0.2
2020+0.1+0.10.0-0.3-0.6-0.8-0.8-0.9-1.2-1.5-1.5-1.4
2021-1.2-1.0-1.0-0.8-0.6-0.5-0.6-0.7-0.9-1.1-1.2-1.2
2022-1.2-1.2-1.3-1.3-1.2-1.0-0.9-1.0-1.1-1.1-1.0-1.0
2023-0.8-0.6-0.4-0.2+0.1+0.4+0.6+0.9+1.1+1.4+1.5+1.5
2024+1.2+0.9+0.5+0.1-0.3-0.5-0.5-0.6-0.8-0.8-0.9-1.1
2025-1.1-0.9-0.7-0.5-0.5-0.4-0.5-0.6-0.8-0.9-0.9-1.0
2026-0.9-0.7-0.5·········

Source: NOAA CPC RONI (ERSST.v5) — 3-month running mean relative Niño 3.4 SST anomalies, 1991–2020 base period. Via CPC RONI table. 2026 values are estimates (subject to revision up to 2 months after posting).

Analysis

Frequent Phase Shifts: What the Record Shows

The 25-year ONI record from 2001 to early 2026 reveals a pattern becoming harder to ignore: phase transitions are accelerating, multi-year events more common, and neutral periods compressing. The triple-dip La Niña of 2020–2023 — the first in 50 years — was followed almost immediately by a significant El Niño in 2023–24, then a weak La Niña in 2024–25, and now a potentially Super El Niño developing in 2026. Four distinct ENSO events in six years. The median Neutral window between events has shortened from 12–18 months in the 1980s–90s to roughly 6–9 months since 2010 — barely enough time for agricultural systems, reservoir storage, and insurance pricing cycles to reset.

9El Niño events
2001–2026
8La Niña events
2001–2026
3Multi-year events
(2+ seasons back-to-back)
~30%Seasons in neutral
2001–2026

The 2023–24 El Niño is particularly instructive as an analogue for 2026. The ECMWF April 2023 ensemble — the closest comparable forecast vintage — projected a moderate event that ultimately peaked at +2.0°C. The April 2026 ECMWF signal is materially stronger than 2023 was at this stage, with a higher model consensus and a larger subsurface heat reservoir. If the analogy holds, 2026 peaks higher than 2023–24 — which itself produced the second-warmest global temperature year on record.

The Compounding Baseline Problem Each El Niño now develops against a warmer background ocean. The 2026 event starts from a baseline 0.3–0.5°C warmer than the 2015–16 Super El Niño’s starting point. This means a moderate 2026 El Niño produces sea surface temperatures equivalent to what a strong El Niño produced a decade ago. A strong 2026 event may cause climate impacts previously associated only with Super El Niño conditions. The +2.0°C threshold for “Super” status is now a lower bar in absolute temperature terms than it was in 1997 or 2015.
Scenario Analysis

Super El Niño Impact: Past Events & 2026–27 Outlook

Only five events have met the Super El Niño threshold (NINO3.4 ≥+2.0°C) since 1950. The 2026–27 cycle is the first with a credible probability of joining that list since 2015–16.

Historical Super El Niño Events

EventPeakDurationIndia MonsoonAustralia AtlanticGlobal TempEcon. Damage
1982–83 +2.1°C 18 months −19% deficit. Maharashtra, Rajasthan droughts Severe drought. Ash Wednesday fires — 75 deaths, $1.3B Below normal 1983 warmest year to that point $32B (2023 USD)
1997–98
Strongest recorded		 +2.4°C 14 months Near-normal — IOD counteracted. Paradox year. Severe drought. GBR mass bleaching. $1.9B Quiet Atlantic; record E. Pacific typhoons 1998 warmest year on record at the time $96B (2023 USD)
2015–16 +2.3°C 16 months Below normal. Kharif stress. HUL/Dabur volume declines in results Severe drought. Black Summer precursor. Record global coral bleaching Below normal; 12 named storms only 2016 warmest year on record (until 2023) $175B (2023 USD)

2026–27 Projected Impact by Scenario

ScenarioPeakProb.IndiaAustralia AtlanticBrazilGlobal Temp 2027Key Portfolio Move
Weak +0.5–+1.0°C ~15% Monsoon near-normal Mild dry; limited fire risk Slight suppression Minimal drought Top-5 likely Modest reinsurer OW only
ModerateBASE +1.0–+1.5°C ~42% 10–15% below normal. India FMCG UW Drought watch Sep. Fire risk elevated Oct–Feb Below normal; 8–10 storms NE drought; hydro stress Q4 Top-3, likely record Full Transition 1 playbook. Reinsurers OW, LNG OW, Eletrobras UW
Strong +1.5–+2.0°C ~30% Significant deficit. FY27 rural miss likely Severe drought; major fire season; IAG/Suncorp claims risk Well below normal; 6–8 storms Energy rationing risk; Eletrobras margin compression Warmest year near-certain Max reinsurer OW. Panama Canal watch. India FMCG max UW
SuperTAIL ≥+2.0°C ~13% Severe failure. IOD wildcard. 2002-scale event possible Catastrophic fire season. Black Summer analogue. GBR bleaching certain Near-inactive; record E. Pacific typhoon season Severe hydro crisis; energy rationing; soy/coffee/sugar crop failure risk +1.7°C above pre-industrial near-certain Tail hedges warranted. CA wildfire insurers max UW. Sugar long setup for early 2027

Super El Niño — Geography Impact Summary

GeographyPrimary ImpactSeverityOnset WindowKey Sectors
🇮🇳 IndiaMonsoon failure — 15–25% deficit. Food inflation. Rural income collapse.Very HighJun–Sep 2026FMCG, rural NBFCs, two-wheelers, agrochemicals
🇦🇺 AustraliaSevere drought Oct–Feb. Catastrophic bushfire season. GBR bleaching event.Very HighSep 2026–Feb 2027IAG, Suncorp, Nufarm, Elders, BHP coal (lagged +)
🌀 Atlantic BasinNear-inactive hurricane season. Reinsurer combined ratio benefit.Strongly PositiveJun–Nov 2026RenRe, Munich Re, Everest Re, Swiss Re — max OW
🇧🇷 BrazilAmazon and NE drought. Hydro depletion. Soy/coffee/sugar disruption.HighAug 2026–Mar 2027Eletrobras, CPFL; ADM, Bunge (trading upside)
🇵🇪 Peru / EcuadorCatastrophic coastal flooding. Humboldt Current collapse. Fisheries disruption.Very HighNov 2026–Mar 2027Fishmeal producers; infrastructure reconstruction
🌏 SE AsiaSevere drought. Peatland fires. LNG demand surge. Palm oil disruption.HighJul–Dec 2026Cheniere, New Fortress Energy; palm oil; LNG shipping
🚢 Panama CanalDraft restrictions likely. 24-vessel/day cap returning. Cape-size rerouting premium.HighAug–Dec 2026Star Bulk, Pacific Basin; LNG tanker rates
🌡️ Global Temperature2027 warmest year on record near-certain. Climate risk repricing across all asset classes accelerates.Very High2027Carbon credits, cooling demand utilities, climate insurance
The 1997–98 Paradox — IOD Wildcard The strongest El Niño on record (1997–98, NINO3.4 +2.4°C) produced above-normal Indian monsoon rainfall. A strongly negative Indian Ocean Dipole counteracted Pacific forcing entirely. If the 2026 IOD turns strongly negative — which cannot be resolved before May–June — the India monsoon failure scenario is substantially reduced even in a Super El Niño. The IOD status in June–July 2026 is the single most important variable for the India call. It cannot be predicted now; it can only be monitored.

Fenrir Research, a division of Yggdrasil Ledger · Climate & Markets Series · Update — April 22, 2026
Sources: NOAA CPC ENSO Diagnostic Discussion (Apr 9, 2026) · IRI/Columbia ENSO Plume (Apr 19, 2026) · ECMWF C3S Seasonal Forecast (Apr 2026) · James Hansen / Columbia University (Apr 15, 2026) · Yale Climate Connections · Carbon Brief · Netweather.tv · BoM ENSO Outlook
This analysis is for informational purposes only. Not investment advice. ENSO probability estimates are analytical judgements based on cited official sources. Super El Niño scenario represents a tail risk, not the base case.

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