El Niño 2026: Conditions and Historical Analogues
Live NOAA data compared to every major ENSO event since 1950
Monthly data current through July 2026. Source: NOAA CPC.
How El Niño is monitored
Of all the indices tracked here, Niño-3.4 is the one that matters most. It needs to stay above +0.5 °C for five consecutive overlapping seasons before an El Niño is officially declared. The Southern Oscillation Index (SOI), a measure of the atmospheric pressure difference between Tahiti and Darwin, acts as a cross-check: if the atmosphere has responded to the ocean warming, it will have turned sharply negative too.
The four Niño regions are fixed boxes in the equatorial Pacific, each capturing a different slice of surface temperature. The SOI measures the pressure difference between Darwin and Tahiti. When that gradient reverses, trade winds weaken, warm water spreads east, and what starts as an ocean anomaly gets amplified by the atmosphere until you have a full El Niño.
Current conditions
At +2.03 °C Niño-3.4 is in very strong El Niño territory, tracking alongside the most intense events on record.
The multivariate view: MEI
Every index above measures one thing. The MEI combines five of them, and at +1.52 for May–Jun 2026 it puts 2026 in strong El Niño territory, confirming the ocean signal is not running ahead of the atmosphere on its own.
The Multivariate ENSO Index (MEI.v2) folds sea surface temperature, sea level pressure, surface zonal and meridional winds, and outgoing longwave radiation into a single number over the tropical Pacific (30°S–30°N), expressed in standard deviations. Because it weighs atmosphere alongside ocean, it is slower to respond than Niño-3.4 but harder to fool: a warm patch of water that the trade winds have not yet reacted to will lift Niño-3.4 without moving the MEI much. The jump from +0.27 in the previous season to +1.52 is the coupled system locking in.
Two-month overlapping seasons, plotted against the second month of each pair. Analogues shown are the top ONI matches. MEI.v2 begins with the Dec 1978–Jan 1979 season, so 1963–64 falls outside the record and cannot be drawn here. Source: NOAA PSL.
Historical context: 75 years of ENSO
Strong El Niño events above +1.5 °C are rare, only four in 75 years of records. What this chart shows is that 2026 is not heading toward an ordinary event.
The chart plots the Oceanic Niño Index (ONI), a 3-month running mean of Niño-3.4 sea surface temperature anomalies and the official NOAA benchmark for declaring El Niño or La Niña conditions. Every event in the observational record is here, showing how frequently they occur, how long they last, and how intense they get. The four annotated peaks are the events most comparable to 2026.
Source: NOAA CPC.
Historical analogues
Measured against the raw Niño-3.4 trajectory, 2026 tracks closest to 1997–98 (r = 0.96). When the long-term warming background is removed (RONI), the closest match shifts to 2018–19 (r = 0.97). 2002–03 appears in both lists.
Each past event is aligned so that month 0 is July of its precursor year. The similarity score captures how closely the shape of the warming matches 2026, not how intense it ultimately got.
ONI uses raw Niño-3.4 values. RONI removes the tropical warming trend to isolate the ENSO forcing pattern. Toggle to compare which events each approach considers most similar to 2026.
The top ONI analogues are the events whose raw Niño-3.4 trajectory most closely matched 2026 over the first 12 months of the event cycle.
The maps below show the full Pacific SST anomaly pattern at the same point in the event cycle. Comparing the spatial footprint helps assess whether the warming is concentrated in the east (EP) or spread toward the dateline (CP).
SST anomaly relative to 1991-2020 climatology. Source: NOAA ERSSTV5.
Niño-3.4 through the full 24-month window for the top ONI analogues. Through the observed period 2026 has tracked between 2023-24 and 1997-98. The dashed magenta line is the IRI forecast plume issued June 2026, averaged over 26 dynamical and statistical models. It peaks at +2.83 °C in SON 2026, where individual members run from +1.46 to +4.73 °C. The shaded band is the middle 50% of members, not that full range, which one or two outliers would otherwise dominate. Relative-ONI models are excluded, since they sit on a different baseline.
Observed monthly data. Month 0 = July of precursor year. Source: NOAA CPC.
Niño 1+2 captures the far eastern Pacific, just off Ecuador and Peru. In Eastern Pacific events this region warms first and most sharply. The 2026 jump from -0.3 °C in March to +1.81 °C in May is one of the fastest accelerations on record for this index, placing 2026 well above where 2023-24 was at the same stage.
Observed monthly data. Source: NOAA CPC.
The SOI provides the atmospheric side of the story. When the SOI turns sharply negative, trade winds weaken and warm water spreads east, amplifying the ocean anomaly through Bjerknes feedback. The 2026 SOI has tracked close to the 1997-98 pattern, suggesting coupling is already well established.
El Niño threshold -1, La Niña +1. Standardised SOI. Source: NOAA CPC.
Full analogue ranking (ONI)
The top three analogues are far ahead of the rest, which tells you the 2026 trajectory is distinctive. Events ranked below 0.5 followed a different path from the start.
All confirmed El Niño events since 1950, ordered by how closely their first 12 months of Niño-3.4 evolution match 2026.
Similarity captures shape, not magnitude. EP/CP type and subsurface precursors are separate dimensions not reflected here.
What's coming
The surface signal is now clear, but what happens next depends on heat stored below the thermocline. Two additional variables would sharpen the peak intensity forecast considerably.
Sources
- NOAA CPC: Monthly Niño region SST indices
- NOAA CPC: Oceanic Niño Index (ONI)
- NOAA CPC: Weekly Niño region SST indices
- NOAA CPC: Standardised SOI
- NOAA PSL: Multivariate ENSO Index v2 (MEI.v2)
- NOAA CPC: ENSO Diagnostic Discussion, June 2026
- IRI Columbia: ENSO Forecasts, June 2026
- NOAA NCEI: Extended Reconstructed SST v5 (ERSSTV5)
- NOAA CPC: Relative Oceanic Niño Index (RONI)