(Update scheduled for the second Thursday of each month)

NOAA CPC ENSO Alert Status (October 8, 2026):   El Niño Advisory (definitions)

El Niño continues to strengthen, with a strong-to-very strong El Niño likely through January-March 2027 (remaining greater than an 83% chance).

NOAA CPC ENSO Forecast
October 8, 2026

Alert Status:   El Niño Advisory
(definitions)


El Niño continues to strengthen, with a strong-to-very strong El Niño likely through January-March 2027 (remaining greater than an 83% chance).



DIAGNOSTIC DISCUSSION:
[Available in various file formats]

El Niño strengthened further last month, with sea surface temperature anomalies exceeding +4.0°C in portions of the eastern equatorial Pacific. Most Niño indices increased in the past month, reaching +2.1°C in Niño-3.4, +3.0°C in Niño-3, and +3.9°C in Niño-1+2. The equatorial subsurface temperature index (average from 180°-100°W) was well above average, reflecting a deeper-than-average thermocline. Subsurface temperatures remained in excess of +10.0°C at depth in the eastern Pacific Ocean.

Low-level westerly wind anomalies and upper-level easterly wind anomalies stretched from the western to the east-central equatorial Pacific. Enhanced convection and rainfall persisted from the central to the eastern Pacific, while anomalies remained suppressed over Indonesia. The traditional and equatorial Southern Oscillation indices were significantly negative. Collectively, the coupled ocean-atmosphere system reflected a strengthening El Niño.

The CPC Official ENSO outlook, which synthesizes multiple models from North America and abroad, indicates El Niño will continue to strengthen through the end of the year [see NOAA's ENSO probability forecast and ENSO Strength Probability forecast]. Chances remain high for a historic event that would exceed the strength of previous El Niño events dating back to 1950 (+2.5°C or more for a 3-month RONI value): the chance is 54% for September-November, 83% for October-December, and 70% for November-January. With an event of this magnitude, the chances of experiencing impacts consistent with El Niño are larger, though not guaranteed (see CPC outlooks for probabilities of seasonal anomalies).

Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). A probabilistic strength forecast is available here.


This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions.


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.

Frequently Used Figures
Click on the figures to access the web pages where these figures are described.

ENSO Blog         NOAA CPC Weekly ENSO Update Presentation

Other Relevant Information

Relative Ocean Niño Index (RONI) and Ocean Niño Index (ONI)     (*** update on the 5th of each month ***)

Per NWS Public Information Statement 26-05, effectively February 1, 2026, the Relative Oceanic Niño index (RONI) is used for official monitoring and prediction of the El Niño-Southern Oscillation (ENSO) phenomenon. See more details here.

• 1950-Present Relative Ocean Niño Index (RONI) Values

• 1950-Present Ocean Niño Index (ONI) Values

• Difference between the legacy ONI and RONI, and their respective time series, from 1950 to present.
  • What is Ocean Niño Index (ONI)?
  • Defining El Niño and La Niña
  • NOAA CPC: Climatology used to calculate the Ocean Niño Index (ONI)
  • NOAA CPC: ONI Climatology Matchup Table

Journal Article: A Relative Sea Surface Temperature Index for Classifying ENSO Events

NOAA CPC's El Niño - Southern Oscillation (ENSO) resources webpage

The World Meteorological Organization (WMO) Climate Normals

El Niño Regions:

Historically Speaking & More:

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

The spring predictability barrier: 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. This is a well-known challenge for forecaster and it can impact statistical models more than dynamical models.

For more information, please contact coralreefwatch@noaa.gov

Disclaimer

The content posted on this web page solely represents the opinions of the authors and does not constitute a statement of policy, decision, or position on behalf of NOAA or the US Government.

The appearance of external links on this World Wide Web site does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site.