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IRI/CPC ENSO Forecast

May 2022 Quick Look

Published: May 19, 2022

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)

In mid-May, Sea Surface Temperatures remain below-average (strengthening slightly) in the central-eastern equatorial Pacific. Key oceanic and atmospheric variables have remained consistent with La Niña conditions, although easterly winds and cold subsurface temperatures have weakened slightly. A La Niña Advisory still remained in place for May 2022. A large majority of the models in the plume predict SSTs to remain below-normal at the level of a weak La Niña until Jun-Aug 2022. Similar to the most-recent official CPC/IRI ENSO Outlook issued on May 12, 2022, the objective model-based ENSO outlook forecasts a continuation of the La Niña event with high probability (62% chance) during Jun-Aug 2022, continuing into boreal fall and early winter with 55-60% likelihood.Similar to the most-recent official CPC/IRI ENSO Outlook issued on April 14, 2022, this objective model-based ENSO outlook also forecasts a continuation of the La Niña event with high probability (61% chance) during May-Jul. However, there is some disagreement between the two forecast methods thereafter. The objective mid-April model-based forecast gives near equal odds to the La Niña and ENSO-neutral categories in boreal summer, with La Niña is favored in Sep-Nov, and Oct-Dec 2022 (54% chance), while the early-April subjective consensus indicates a continuation of La Niña with a 50-55% chance throughout both summer and fall.

Figures 1 and 3 (the official ENSO probability forecast and the objective model-based ENSO probability forecast, respectively) are often quite similar. However, occasionally they may differ noticeably. There can be several reasons for differences. One possible reason is that the human forecasters, using their experience and judgment, may disagree to some degree with the models, which may have known biases. Another reason is related to the fact that 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, so that between the second and the third Thursday of the month, the official forecast (Fig. 1) has just been updated, while the model-based forecasts (Figs. 3 and 4) are still from the third Thursday of the previous month. On the other hand, from the third Thursday of the month until the second Thursday of the next month, the model-based forecasts are more recently updated, while the official forecasts remain from the second Thursday of the current month.
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

CPC/IRI ENSO Update

Published: May 12, 2022

El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued jointly by the Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society

ENSO Alert System Status: La Niña Advisory

SynopsisThough La Niña is favored to continue, the odds for La Niña decrease into the late Northern Hemisphere summer (58% chance in August-October 2022) before slightly increasing through the Northern Hemisphere fall and early winter 2022 (61% chance).

Below-average sea surface temperatures (SSTs) persisted during April across most of the central and eastern equatorial Pacific Ocean (Fig. 1). Over the past month, the Niño index values decreased, with the latest weekly values ranging from -1.1ºC to -1.5ºC (Fig. 2), which are quite negative for this time of year.  Subsurface temperatures anomalies (averaged between 180º-100ºW and 0-300m depth) remained negative (Fig. 3), reflecting an extensive area of below-average temperatures from the surface to ~100m depth across the central and eastern equatorial Pacific Ocean (Fig. 4). For the monthly average, low-level easterly and upper-level westerly wind anomalies dominated the equatorial Pacific.  Convection remained significantly suppressed around the Date Line and was enhanced over the Philippines (Fig. 5). Overall, the coupled ocean-atmosphere system reflected the continuation of La Niña.

The most recent IRI/CPC plume average for the Niño-3.4 SST index forecasts borderline La Niña conditions during the Northern Hemisphere summer, with increasing odds for La Niña into the fall (Fig. 6). Similar to last month, the forecaster consensus predicts Niño-3.4 index values to weaken into the summer, but remaining below the threshold of La Niña (Niño-3.4 values equal to or less than -0.5ºC).  In the near-term, westerly wind anomalies are predicted for mid-late May which supports the weakening of below-average surface and subsurface oceanic temperatures in the coming months.  However, much of the model guidance is also hinting at a re-strengthening of La Niña conditions again in the fall and upcoming winter.  In summary, though La Niña is favored to continue, the odds for La Niña decrease into the late Northern Hemisphere summer (58% chance in August-October 2022) before slightly increasing through the Northern Hemisphere fall and early winter 2022 (61% chance; click CPC/IRI consensus forecast for the chances in each 3-month period).

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Additional perspectives and analysis are also available in an ENSO blog. A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 9 June 2022. To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: ncep.list.enso-update@noaa.gov.



Season La Niña Neutral El Niño
AMJ 100 0 0
MJJ 87 13 0
JJA 69 31 0
JAS 59 39 2
ASO 58 38 4
SON 61 35 4
OND 61 34 5
NDJ 61 34 5
DJF 58 37 5

IRI ENSO Forecast

IRI Technical ENSO Update

Published: May 19, 2022

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 SST anomaly for NINO3.4 during the Feb-Apr season was -0.85 C, and for the month of April it was -0.95 C. The most recent weekly (11 May 2022) anomaly in the NINO3.4 region was -1.1 C, indicating a continuation of the current La Niña event. The IRI’s definition of El Niño, like NOAA/Climate Prediction Center’s, requires that the SST anomaly in the NINO3.4 region (5S-5N; 170W-120W) exceed 0.5 C. Similarly, for La Niña, the anomaly must be -0.5 C or less.

Many of the key atmospheric variables remain indicative of La Niña conditions. The traditional and equatorial Southern Oscillation Indices are positive and intensified further during April 2022, and continued to be so through mid-May 2022. The low-level wind anomalies are near normal and upper-level wind anomalies remain westerly across the tropical Pacific; anomalously dry conditions have been observed around the date line. Across most of the equatorial Pacific Ocean, temperatures are below average near the surface, extending down to 100 meters on the eastern side. However, subsurface temperatures in the western and central Pacific are warmer than average, mainly at depths of 100-200 meters.

In summary, tropical Pacific atmospheric and oceanic conditions are consistent with La Niña. A La Niña advisory is still in place.

Expected Conditions

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

What is the outlook for the ENSO status going forward? El Niño/Southern Oscillation (ENSO) Diagnostic Discussionissued jointly on 12 May 2022 by the Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society indicates a continuation of the current La Niña event during the Northern Hemisphere summer.

The latest set of model ENSO predictions from mid-May is now available in the IRI/CPC ENSO prediction plume. These are used to assess the probabilities of the three possible ENSO conditions 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 average forecast, and its width is 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. Using this method, the chances of La Niña are 62% for the Jun-Aug season, while those of the ENSO-neutral category are 37%. The probability of La Niña for the subsequent seasons is forecasted to be between 55-60%, decreasing to 47% in Dec-Feb and 37% in Jan-Mar. ENSO-neutral is the second most likely category throughout the forecast period, while El Niño likelihoods remain very low. 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 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.

In summary, the probabilities derived from the models in the IRI/CPC plume indicate a preference for the continuation of the La Niña during the forecast period with moderate probability. The likelihood for El Niño development remains very low.

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 the official outlooks, which are generated and issued early in the month by CPC and IRI, and which will include some human judgment in combination with the model guidance.

Season La Niña Neutral El Niño
MJJ 81 19 0
JJA 62 37 1
JAS 56 41 3
ASO 57 39 4
SON 58 36 6
OND 60 33 7
NDJ 58 34 8
DJF 47 42 11
JFM 37 50 13

IRI ENSO Forecast

IRI/CPC Model-Based Probabilistic ENSO Forecast

Published: May 19, 2022

A purely objective ENSO probability forecast, based on regression, using as input the model predictions from the plume of dynamical and statistical forecasts shown in the ENSO Predictions Plume. Each of the forecasts is weighted equally. It is updated near or just after the middle of the month, using forecasts from the plume models that are run in the first half of the month. It does not use any human interpretation or judgment. This is updated on the third Thursday of the month.



Season La Niña Neutral El Niño
MJJ 81 19 0
JJA 62 37 1
JAS 56 41 3
ASO 57 39 4
SON 58 36 6
OND 60 33 7
NDJ 58 34 8
DJF 47 42 11
JFM 37 50 13

IRI ENSO Forecast

CPC/IRI Official Probabilistic ENSO Forecast

Published: May 12, 2022

The official CPC/IRI ENSO probability forecast, based on a consensus of CPC and IRI forecasters. It is updated during the first half of the month, in association with the official CPC/IRI ENSO Diagnostic Discussion. It is based on observational and predictive information from early in the month and from the previous month. It uses human judgment in addition to model output, while the forecast shown in the Model-Based Probabilistic ENSO Forecast relies solely on model output. This is updated on the second Thursday of every month.



Season La Niña Neutral El Niño
AMJ 100 0 0
MJJ 87 13 0
JJA 69 31 0
JAS 59 39 2
ASO 58 38 4
SON 61 35 4
OND 61 34 5
NDJ 61 34 5
DJF 58 37 5

IRI ENSO Forecast

IRI/CPC ENSO Predictions Plume

Published: May 19, 2022

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 (2022 – 2023)
Model MJJ JJA JAS ASO SON OND NDJ DJF JFM
Dynamical Models
NASA GMAO -1.59 -1.70 -1.71 -1.81 -1.94 -1.95 -1.76
NCEP CFSv2 -0.99 -0.88 -0.75 -0.69 -0.74 -0.77 -0.75
JMA -0.86 -0.71 -0.63 -0.67 -0.76
BCC_CSM11m -0.37 -0.03 0.17 0.25 0.30 0.42 0.65 0.94 1.25
SAUDI-KAU -0.58 -0.28 -0.13 -0.04 0.07 0.26 0.48 0.66 0.79
LDEO -0.71 -0.41 -0.20 -0.13 -0.18 -0.21 -0.26 -0.34 -0.43
AUS-ACCESS -0.60 -0.43 -0.37 -0.40
ECMWF -0.63 -0.40 -0.30 -0.28 -0.29
UKMO -0.83 -0.81 -0.82 -0.92
KMA -0.21 -0.18 -0.25 -0.35 -0.19
IOCAS ICM -1.15 -1.17 -1.29 -1.53 -1.84 -2.12 -2.37 -2.54 -2.50
COLA CCSM4 -0.87 -0.90 -0.99 -1.01 -1.05 -1.04 -0.88 -0.54 -0.10
MetFRANCE -1.32 -1.10 -1.02 -0.90 -0.98 -1.15 -1.30
SINTEX-F -0.72 -0.66 -0.58 -0.54 -0.51 -0.41 -0.25 -0.07 0.08
CS-IRI-MM -0.47 -0.31 -0.27 -0.34 -0.44 -0.50
GFDL SPEAR -0.48 -0.28 -0.24 -0.34 -0.49 -0.56 -0.45 -0.19 0.13
CMC CANSIP -0.96 -0.85 -0.82 -0.88 -1.04 -1.19 -1.20 -1.07 -0.84
Average, Dynamical models -0.785 -0.654 -0.599 -0.623 -0.672 -0.769 -0.735 -0.394 -0.202
Statistical Models
NTU CODA -0.91 -0.89 -0.90 -0.98 -1.17 -1.38 -1.45 -1.43 -1.20
BCC_RZDM -0.60 -0.45 -0.43 -0.49 -0.57 -0.68 -0.80 -0.84 -0.78
CPC MRKOV -0.83 -0.69 -0.57 -0.43 -0.29 -0.12 0.08 0.27 0.39
CPC CA -0.61 -0.51 -0.50 -0.49 -0.53 -0.54 -0.51 -0.33 -0.09
CSU CLIPR -0.60 -0.57 -0.54 -0.51 -0.48 -0.44 -0.41 -0.35 -0.30
IAP-NN -0.67 -0.51 -0.36 -0.21 -0.06 0.08 0.16 0.25 0.32
UCLA-TCD -0.71 -0.69 -0.77 -0.91 -1.05 -1.14 -1.13 -1.03 -0.84
Average, Statistical models -0.705 -0.616 -0.582 -0.575 -0.592 -0.604 -0.579 -0.495 -0.357
Average, All models -0.762 -0.643 -0.594 -0.609 -0.646 -0.708 -0.675 -0.441 -0.275

Discussion of Current Forecasts

The majority of both dynamical and statistical model forecasts issued in mid-May 2022 indicate below-normal SSTs in the equatorial Pacific and a continuation of the current La Niña event during boreal summer (62% chance in Jun-Aug 2022). There is a 55-60% chance for a weak La Niña to persist thereafter before decreasing during boreal winter. A more confident forecast can be expected through continued monitoring during the coming months, since ocean-atmosphere interactions are sensitive and variable at this time of year (the so-called ENSO spring predictability barrier). Based on the multi-model mean prediction, and the expected skill of the models by start time and lead time, the probabilities (X100) 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
MJJ 81 19 0
JJA 62 37 1
JAS 56 41 3
ASO 57 39 4
SON 58 36 6
OND 60 33 7
NDJ 58 34 8
DJF 47 42 11
JFM 37 50 13

Summary of forecasts issued over last 22 months

The following plots show 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 also 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. The first plot shows forecasts for dynamical models, the second for statistical models, and the third for all models. For less difficult readability, forecasts are shown to a maximum of only the first five lead times. Below the third plot, we provide a mechanism for highlighting the forecasts of one model at a time against a background of more lightly colored lines for all other models.


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.

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 1971-2000 period as the base period, or a period not very different from it.

IRI ENSO Forecast

Forecast Probability Distribution Based on the IRI/CPC ENSO Prediction Plume

Published: May 19, 2022


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.


  • 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.

  • 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.

The CPC ENSO forecast is released at 9am (Eastern Time) on the second Thursday of each month.

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.