ENSO Forecast Navigation

ENSO Forecasts

ENSO Forecast

January 2026 Quick Look

Published: January 20, 2026

A monthly summary of the status of El Niño, La Niña, and the Southern Oscillation, or ENSO, based on the NINO3.4 index (120-170W, 5S-5N)

As of mid-January 2026, the equatorial Pacific remains in a La Niña state. The CCSR/IRI ENSO plume forecast places the probability of La Niña at 31% for Jan–Mar 2026 and shifts the odds in favor of ENSO-neutral conditions (about 69%) for the same period. ENSO-neutral remains the dominant category through May-Jul 2026. Beyond that, El Niño probabilities become higher than ENSO-neutral, although they remain in the range of 48% to 51%, with ENSO-neutral still the second most likely outcome.

Figures 1 ((the official CPC ENSO probability forecast) and 3 (the objective model-based IRI ENSO probability forecast) are often quite similar. However, occasionally they may differ noticeably. There can be several possible reasons for differences. One is the human forecasters, using their experience and judgment, may disagree to some degree with the models, which may have known biases. Another reason is the models are not run at the same time that the forecasters make their assessment, so that the starting ENSO conditions may be slightly different between the two times. The charts on this Quick Look page are updated at two different times of the month, typically about a week apart, with the IRI forecast run later. Also note that the CPC forecast starts on the previous season while the IRI forecast starts on the current season.
Click on the for more information on each figure.

Historically Speaking

    El Niño and La Niña events tend to develop during the period Apr-Jun and they
  • Tend to reach their maximum strength during October - February
  • Typically persist for 9-12 months, though occasionally persisting for up to 2 years
  • Typically recur every 2 to 7 years

IRI ENSO Forecast

IRI Technical ENSO Update and Model-Based Probabilistic ENSO Forecast

Published: January 20, 2026

Note: The SST anomalies cited below refer to the OISSTv2 SST data set, and not ERSSTv5. OISSTv2 is often used for real-time analysis and model initialization, while ERSSTv5 is used for retrospective official ENSO diagnosis because it is more homogeneous over time, allowing for more accurate comparisons among ENSO events that are years apart. These two products may differ, particularly during ENSO events. The difference between the two datasets may be as much as 0.5 °C. Additionally in some years, the ERSSTv5 may tend to be cooler than OISSTv2 in the context of warming trends, because ERSSTv5 is expressed relative to a base period that is updated every 5 years, while the base period of OISSTv2 is updated every 10 years. In February 2021, both datasets were updated to reflect the 1991-2020 climatology period.

Recent and Current Conditions

The observed SST anomaly in the NINO3.4 region during the Oct–Dec 2025 season was -0.59 °C, and for December 2025, it was -0.61 °C. The most recent weekly average (week centered on January 14, 2026) of the NINO3.4 index was -0.7 °C. These values indicate that Pacific sea-surface temperature anomalies have been experiencing weak La Niña conditions across the equatorial Pacific. The IRI’s definition of El Niño, similar to NOAA/Climate Prediction Center’s, requires that the monthly SST anomaly in the NINO3.4 region (5°S-5°N; 170°W-120°W) exceed +0.5 °C. Similarly, for La Niña, the anomaly must be -0.5 °C or colder.

By mid-January 2026, weak La Niña conditions have been present in both the atmosphere and ocean. In December 2025, the Southern Oscillation Index (SOI) was +0.1, while the equatorial SOI was +0.9, indicating a mismatch between the two indices during the month. However, the most recent 30-day (ending on 18 January 2026) SOI value is firmly within La Niña territory. Low-level winds (850 hPa) were blowing close to average across the east-central and eastern Pacific. Enhanced convection and increased rainfall were evident over parts of Indonesia, marked by below-average OLR, while suppressed convection and reduced precipitation dominated around the Date Line with above-average OLR. Subsurface temperature anomalies weakened during November and December 2025 but still remained negative in the far eastern Pacific (roughly 100°W–80°W). Meanwhile, above-average subsurface temperatures strengthened in the western half of the Pacific and expanded further eastward; however, the warming remained confined to depth and was relatively weak in magnitude.

Expected Conditions

Note – Only models that produce a new ENSO prediction every month are considered in this statement.

The El Niño/Southern Oscillation (ENSO) Diagnostic Discussion, released on 08 January 2026 by the Climate Prediction Center (CPC)/NCEP/NWS, maintained a “La Niña Advisory”, followed by a 75% chance of a transition to ENSO-neutral during January-March 2026, while ENSO-neutral is likely through at least Northern Hemisphere late spring 2026.

The latest set of ENSO prediction models from mid-January 2026 is now available in the CCSR IRI ENSO prediction plume. These are used to assess the probabilities of the three ENSO categories by using the average value of the NINO3.4 SST anomaly predictions from all models in the plume, equally weighted. A standard Gaussian error is imposed over that averaged forecast, with its width determined by an estimate of overall expected model skill for the season of the year and the lead time. Higher skill results in a relatively narrower error distribution, while low skill results in an error distribution with width approaching that of the historical observed distribution.

According to the January 2026 CCSR/IRI ENSO plume forecast, the probability of La Niña conditions persisting during Jan–Mar (JFM) 2026 is 31%, while ENSO-neutral conditions are the next most likely outcome, with an estimated probability of 69%. From Feb–Apr through May-Jul 2026, the outlook favors ENSO-neutral conditions, with probabilities ranging from 86% to 58% across the overlapping seasonal periods. During this period, La Niña probabilities remain low (between 13% to 5%), while the odds of El Niño gradually increase from 1% to 37% by May–Jul 2026. In the final four overlapping seasons of the forecast (Jun-Aug, Jul–Sep, Aug–Oct, and Sep–Nov), El Niño becomes the most likely outcome; however, probabilities remain low (between 48% to 51%), with ENSO-neutral the next most likely category. Caution is advised when interpreting these longer-lead ENSO forecasts, as they extend through the boreal spring predictability barrier; accordingly, long-range outlooks should be viewed with appropriate uncertainty, even if they suggest a possible emerging outcome. A plot of the probabilities summarizes the forecast evolution. The climatological probabilities for La Niña, ENSO-neutral, and El Niño conditions vary seasonally, and are shown by the lines on the plot, and are given in a table at the bottom of this page for each 3-month season.

Caution is advised in interpreting the forecast distribution from the Gaussian standard error as the actual probabilities, due to differing biases and performance of the different models. In particular, this approach considers only the mean of the predictions, and not the total range across the models, nor the ensemble range within individual models. At longer leads, the skill of the models degrades, and uncertainty in skill must be convolved with the uncertainties from initial conditions and differing model physics, which leads to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution.

It is worth noting that the Relative Oceanic Niño Index (RONI), which measures sea surface temperature anomalies in the eastern equatorial Pacific relative to the rest of the equatorial band, has consistently and increasingly exceeded the −0.5 La Niña threshold for the past several overlapping seasons. For Jul–Sep, Aug–Oct, Sep–Nov, and Oct-Dec 2025, the RONI was -0.63, -0.77, -0.87, and -0.92 °C respectively. The Pacific Decadal Oscillation (PDO) Index in November 2025 recorded a value of −1.01.

A caution regarding the model-based ENSO plume predictions (released mid-month) is that factors such as known specific model biases and recent changes in the tropical Pacific that the models may have missed, are not considered. This approach is purely objective. Those issues are taken into account in CPC’s official outlooks, which are issued early in the month, and which will include some human judgment in combination with the model guidance.

IRI ENSO Forecast Histogram Image
Season La Niña Neutral El Niño
JFM 31 69 0
FMA 13 86 1
MAM 5 88 7
AMJ 3 72 25
MJJ 6 58 36
JJA 6 46 48
JAS 7 42 51
ASO 11 41 48
SON 13 37 50

ENSO Forecast

IRI ENSO Predictions Plume

Published: January 20, 2026

Note on interpreting model forecasts

The following graph and table show forecasts made by dynamical and statistical models for SST in the Nino 3.4 region for nine overlapping 3-month periods. Note that the expected skills of the models, based on historical performance, are not equal to one another. The skills also generally decrease as the lead time increases. Thirdly, forecasts made at some times of the year generally have higher skill than forecasts made at other times of the year--namely, they are better when made between June and December than when they are made between February and May. Differences among the forecasts of the models reflect both differences in model design, and actual uncertainty in the forecast of the possible future SST scenario.

Interactive Chart

You can highlight a specific model by hovering over it either on the chart or the legend. Selecting An item on the legend will toggle the visibility of the model on the page. You can also select DYN MODELS or STAT MODELS to toggle them all at once. Clicking on the "burger" menu above the legend will give you options to download the image or expand to full screen. If you have any feedback on this new feature, please let us know at webmaster@iri.columbia.edu.

List of Models Used

Forecast SST Anomalies (deg C) in the Nino 3.4 Region

Seasons (2026 – 2026)
Model JFM FMA MAM AMJ MJJ JJA JAS ASO SON
Dynamical Models
AUS-ACCESS -0.07 0.33 0.67 0.90
AUS-RELATIVE -0.50 -0.10 0.23 0.50
BCC DIAP -0.25 -0.09 0.03 0.15 0.29 0.43 0.59 0.70 0.86
CMC CANSIP -0.39 -0.20 -0.01 0.18 0.40 0.58 0.67 0.69 0.72
COLA CCSM4 -0.40 -0.19 0.08 0.40 0.71 1.01 1.27 1.45 1.55
CS-IRI-MM -0.36 -0.07 0.18 0.40 0.63 0.92
GFDL SPEAR 0.09 0.39 0.63 0.85 1.06 1.23 1.27 1.29 1.34
IOCAS ICM -0.50 -0.42 -0.27 -0.14 -0.04 0.04 0.10 0.13 0.12
JMA -0.32 -0.05 0.18 0.41 0.65
KMA -0.15 0.17 0.46 0.71
LDEO -0.44 -0.35 -0.29 -0.24 -0.19 -0.15 -0.20 -0.28 -0.32
MetFRANCE -0.71 -0.48 -0.26 -0.01 0.23
NASA GMAO -0.51 -0.14 0.23 0.56 0.86 1.09 1.23
NCEP CFSv2 -0.32 0.00 0.21 0.35 0.48 0.66 0.87
SINTEX-F -0.45 -0.22 0.03 0.30 0.59 0.83 0.93 0.94 0.95
UKMO -0.18 0.10 0.40 0.64
Average, Dynamical models -0.341 -0.082 0.156 0.372 0.472 0.664 0.748 0.702 0.745
Statistical Models
BCC STATISTICAL -0.42 -0.32 -0.25 -0.17 -0.07 0.01 0.05 0.06 0.07
CPC MRKOV -0.88 -0.76 -0.64 -0.52 -0.43 -0.37 -0.30 -0.23 -0.15
CSU CLIPR -0.43 -0.39 -0.35 -0.31 -0.31 -0.30 -0.30 -0.34 -0.38
IAP-NN -0.41 -0.27 -0.13 0.00 0.12 0.23 0.32 0.38 0.41
TONGJI-ML -0.58 -0.67 -0.51 -0.22 0.09 0.29 0.28 0.11 -0.07
UCLA-TCD -0.11 0.11 0.33 0.51 0.65 0.73 0.77 0.77 0.75
UW PSL-CSLIM -0.20 0.10 0.40 0.66 0.86 0.99 1.07 1.15 1.25
UW PSL-LIM -0.32 -0.18 -0.05 0.07 0.20 0.32 0.40 0.45 0.47
XRO -0.45 -0.34 -0.22 -0.09 0.03 0.14 0.21 0.27 0.35
Average, Statistical models -0.422 -0.303 -0.158 -0.008 0.128 0.226 0.278 0.291 0.299
Average, All models -0.370 -0.161 0.043 0.235 0.324 0.456 0.513 0.471 0.494

Discussion of Current Forecasts

The CCSR/IRI ENSO prediction plume indicates a high likelihood of ENSO-neutral conditions during Jan–Mar 2026. The multimodel mean of statistical and dynamical models suggests that La Niña is likely to transition to ENSO-neutral in Jan–Mar 2026 (69% chance), with ENSO-neutral conditions remaining the dominant category through May–Jul 2026 (58% chance). Over this period, the probability of El Niño development gradually increases from 1% in Feb–Apr to 37% by May–Jul 2026, and El Niño becomes the leading category during the final four overlapping seasons of the forecast(Jun to Nov), although probabilities remain in the low (between 48% to 51%). However, such long-lead forecasts remain highly uncertain, as they pass through the spring predictability barrier. Based on the multi-model mean (Dynamical andStatistical models) prediction, and the expected skill of the models by start time and lead time, the probabilities (in %) for La Niña, ENSO-neutral and El Niño conditions (using -0.5 °C and 0.5 °C thresholds) over the coming 9 seasons are:

Season La Niña Neutral El Niño
JFM 31 69 0
FMA 13 86 1
MAM 5 88 7
AMJ 3 72 25
MJJ 6 58 36
JJA 6 46 48
JAS 7 42 51
ASO 11 41 48
SON 13 37 50

Summary of forecasts issued over last 22 months

The following interactive plot shows the model forecasts issued not only from the current month (as in the plot above), but also from the 21 months previous to this month. The observations are shown up to the most recently completed 3-month period. The plots allow comparison of plumes from the previous start times, or examination of the forecast behavior of a given model over time.
Hovering over any single model will highlight that particular model in the chart.
Clicking a particular model will hide/show that model in the chart.
At the bottom of the plot, you can select which models to show in the chart: all the models, the dynamical models only, or the statistical models only.

Notes on the data 

Only models producing forecasts on a monthly basis are included. This means that some models whose forecasts appear in the Experimental Long-Lead Forecast Bulletin (produced by COLA) do not appear in the table.

Once an IRI ENSO probability forecast has been published, the results stand even if a model reports an error and changes their data. When this happens we will update the plume with the model's correct values even though our forecast hasn't changed. What this means is that our forecast is always the same, but the underlying data may be different from what we based our forecast on.

The SST anomaly forecasts are for the 3-month periods shown, and are for the Nino 3.4 region (120-170W, 5N-5S). Often, the anomalies are provided directly in a graph or a table by the respective forecasting centers for the Nino 3.4 region. In some cases, however, they are given for 1-month periods, for 3-month periods that skip some of the periods in the above table, and/or only for a region (or regions) other than Nino 3.4. In these cases, the following means are used to obtain the needed anomalies for the table:

  • Temporal averaging
  • Linear temporal interpolation
  • Visual averaging of values on a contoured map

The anomalies shown are those with respect to the base period used to define the normals, which vary among the groups producing model forecasts. They have not been adjusted to anomalies with respect to a common base period. Discrepancies among the climatological SST resulting from differing base periods may be as high as a quarter of a degree C in the worst cases. Forecasters are encouraged to use the standard 1991-2020 period as the base period, or a period not very different from it.

ENSO Forecast

Forecast Probability Distribution Based on the IRI ENSO Prediction Plume

Published: January 20, 2026

The plots on this page show predictions of seasonal (3-month average) sea surface temperature (SST) anomaly in the Niño3.4 region in the east-central tropical Pacific (5°N-5°S, 120°-170°W), covering the nine overlapping seasons beginning with the current month. The predictions are based on the large (20+) set of dynamical and statistical models in the plume of model ENSO predictions.

  • Model Based Prediction Percentiles Image

    Figure 5

    Predictions of ENSO are probabilistic. The ensemble mean prediction is only a best single guess. On either side of that prediction, there is a substantial uncertainty distribution, or error tolerance. The second plot (Figure 2) shows the estimated probability distribution of the predictions, showing a set of percentiles within that distribution for each lead time. The distribution is modeled as a normal (Gaussian) distribution, so that the overall mean forecast represents the center, or 50 percentile, in the distribution. The overall mean is formed using equal weighting among all models. On either side, other percentile values are shown symmetrically, ranging from 1 to 99 and including some intermediate percentiles (5 and 95, 15 and 85, and 25 and 75). The plot enables a user to estimate the probability of the Niño3.4 SST anomaly to be greater or less than some critical value, or within some interval. If, for example, the 85 percentile falls at 1.8° C above average, the probability of the SST exceeding 1.8° C can be estimated at 15%. Probabilities for exceeding or not exceeding values not exactly on percentile line can be roughly interpolated by eye. The overall width of the probability distribution is derived from the historical skill of the hindcasts of the models, from 1982 to present, for the specific forecast start time and lead time. This method of defining the probability distribution represents one of two general approaches, the other approach being a direct counting of ensemble members within each of the percentile bands. This second approach assumes that the ensemble spreads of the models are true representations of the uncertainty. Individual model spreads have often been found to be somwehate narrower than they should be, although in multi-model ensembles this tendency has been shown to be milder or even eliminated.

  • Model Based Prediction Distribution Image

    Figure 6

    Figure 6, sometimes called a spaghetti diagram, shows synthetically generated prediction scenarios that are equally likely. Here, 100 scenarios are shown; any number can be generated for such a diagram. Each scenario is produced using a random number generator, combined with knowledge of the mean forecast and its uncertainty, as well as the amount of persistence of anomalies. The degree of persistence of anomalies is based on the correlation of prediction errors from one lead time to another. In other words, the individual lines are designed to show the correct amount of persistence as expected in nature, rather than jumping around more randomly from one lead time to the next. The uncertainty and persistence statistics are based on the set of 7 NMME (North American Multimodel Ensemble) models, as it is assumed that these statistics are approximately applicable to all of the models. Sometimes the “spaghetti density” may appear asymmetric about the mean of all the forecasts or outside of the 85 and 15 percentile lines. This is purely sampling variability, and would not occur if many thousands of such lines were plotted. But with that many lines, most of the plot would be too crowded to get a sense of the behavior of the lines near the center of the distribution. The main purpose of the diagram is to serve users who want to assess realistic individual scenarios of ENSO behavior rather than statistical summaries of the forecast like the percentiles shown in the second plot.

IOD Forecast

Published: January 20, 2026

Note: The Dipole Mode Index is calculated based on the ERSSTv5 data. To account for evolving background conditions and long-term warming, SST anomalies were calculated relative to a sliding monthly climatology. For each month in the time series, the climatology was computed as the mean SST for that calendar month over the prior 30 years. The Dipole Mode Index (DMI) is then defined as the difference in sea surface temperature anomalies between the western equatorial Indian Ocean (50°E–70°E, 10°S–10°N) and the southeastern equatorial Indian Ocean (90°E–110°E, 10°S–0°), and is used to quantify the strength and phase of the Indian Ocean Dipole (IOD).

Current Conditions

In December 2025, the observed Dipole Mode Index was –0.55 °C, indicating that negative IOD conditions persisted across the Indian Ocean. According to the CCSR@NASA-GISS/IRI’s criteria for defining positive and negative Indian Ocean Dipole (IOD) events, a positive IOD phase is defined when the DMI exceeds +0.4 °C, and a negative IOD when it falls below −0.4 °C. The IOD is considered inactive (neutral) when the DMI lies between −0.4 °C and +0.4 °C.

Model-Based IOD Outlook: Deterministic Forecasts from the NMME

Forecasts from the latest set of operational models in the North American Multi-Model Ensemble (NMME) project are used to construct deterministic IOD forecasts from each individual model using its ensemble mean DMI to form an IOD forecast plume. The IOD plume plot shows the latest set of predictions from CESM1, CFSv2, CanESM5, GEM-NEMO, NASA, GFDL-SPEAR, along with their equally weighted multi-model mean (MME). The observed Dipole Mode Index (DMI; shown in black) exhibited a consistent downward trend from May to December 2025, transitioning into negative IOD conditions by late August and reaching its most negative value (peak intensity of the negative phase) in October 2025. Forecasts for January 2026 indicate that all models in the plume favor IOD-neutral conditions (DMI between −0.4°C and +0.4°C). Beyond January and through the end of the forecast horizon, most deterministic model forecasts stay in the IOD-neutral range (DMI between −0.4°C and +0.4°C), with GFDL-SPEAR the main exception in indicating a shift toward positive IOD conditions (DMI above +0.4°C), while the multi-model ensemble mean (MME) remains IOD-neutral.

Probabilistic IOD Forecasts from the NMME

Based on January 2026 initialization data, the model-based probabilistic forecast of the Indian Ocean Dipole was generated by CCSR@NASA-GISS/IRI to assess potential phase developments. Probabilities are computed using a counting method, where each ensemble member from the contributing models is evaluated individually, and pooled to determine the likelihood of a negative, neutral, or positive IOD phase for the upcoming months. Climatological probabilities for each IOD phase, based on historical data, are shown as dotted lines for reference. Throughout the January–July 2026 outlook, IOD-neutral conditions are the most likely state. The main evolution in the probabilities is a gradual increase in positive IOD likelihood and a corresponding decrease in negative IOD likelihood, while neutral remains dominant across the forecast horizon.

In summary, January 2026 favors IOD-neutral conditions, with neutrality remaining the dominant signal for the rest of the outlook.

January 20, 2026 IOD Model Based Forecast
Historical SST Anomalies Image

References

Real-time ENSO forecast skill evaluated over the last two decades, with focus on the onset of ENSO events. Ehsan, M.A., L’Heureux, M.L., Tippett, M.K., Robertson, A.W, Turmelle, J.P., npj Clim Atmos Sci, 2024.

The IRI ENSO forecast is released on the 19th of each month. If the 19th falls on a weekend or holiday, it is released on the closest business day.

Forecast and model data used in our probabilistic forecast can be accessed by submitting a Request to Access IRI ENSO Data.

All data from this website is covered under the Creative Commons Attribution 4.0 License. When citing IRI ENSO images or data, please use "Images [or Data] provided by The International Research Institute for Climate and Society, Columbia University Climate School", with a link to https://iri.columbia.edu/ENSO.