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Atlantic Niño

Monitoring and understanding tropical Atlantic climate variability

The Atlantic Niño is the dominant mode of interannual climate variability in the equatorial Atlantic Ocean. Although generally weaker than its Pacific counterpart (El Niño), it exerts a profound influence on regional climate, marine ecosystems, fisheries, and rainfall over West Africa and northeastern South America. This page provides an overview of the phenomenon, the physical processes that govern its evolution, monitoring products, datasets, forecasts, and links to current research.

a) Regression of sea surface temperature (colors, in ◦C), sea level pressure (blue and red contours, in hPa) and surface winds (arrows) anomalies onto the standardized JJAS Atlantic Niño index, over the period 1901 – 2010. Green contours denote significant SSTAs at 95% confidence level (Student-test). b) Same as in a), but for the vertically integrated moisture flux convergence (colors) and vertically integrated moisture flux (arrows) anomalies. Positive SST anomalies develop over the eastern and central equatorial Atlantic (ATL3 region), accompanied by anomalous westerly surface winds along the equator. These atmospheric anomalies reduce equatorial upwelling, deepen the eastern thermocline, and reinforce the warm SST anomalies through the Atlantic Bjerknes feedback. Positive (negative) moisture flux convergence indicates regions where atmospheric moisture accumulates (diverges), favouring enhanced (suppressed) precipitation. Source: Worou et al. (2020)

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Monitoring the current state

This section will be updated automatically using GitHub Actions.

Current Atlantic Niño Index

Last 3 years of the standardized detrended Atlantic Niño index

Standardized detrended anomaly of the Atlantic Niño index

Equatorial Atlantic Sea surface temperature evolution

Seasonal cycle of sea surface temperature over the ATL3 region (3°S–3°N, 20°W–0°) in the equatorial Atlantic Ocean. Reference period: 1854-2025 period.

Variation of the annual sea surface temperature anomalies over the equatorial Atlantic region. Anomalies are computed relative to the 1854-2025 period.

Two weeks averages of sea surface temperatures and their anomalies

Thermocline depth anomalies

Figure. Sea surface temperature anomalies show the development of Atlantic Niña event, in relation with the El-Niño growing phase in the equatorial Pacific. Source: NOAA CPC, Climate Prediction Center (2026).

NoteStart and stop the animation at any time from here:

Figure. Sea surface temperature anomalies show the development of Atlantic Niña event, in relation with the El-Niño growing phase in the equatorial Pacific. Source: NOAA CPC, Climate Prediction Center (2026).

Recent daily sea surface temperature anomalies

Surface winds

Source: Climate Reanalyzer (Climate Change Institute, University of Maine).

Sea surface temperature anomalies animation

Global SST anomalies

Figure. Global sea surface temperature anomalies (°C) relative to the 1991–2020 climatology. Source: NOAA CPC, Climate Prediction Center (2026).

Sea surface height anomalies animation

SSH anomalies

Figure. Sea surface height (SSH) anomalies. Source: NOAA CPC, Climate Prediction Center (2026).

Thermocline depth and subsurface conditions, animations

Thermocline depth anomalies

Figure. Thermocline depth anomalies, indicated by the 20°C isotherm depth. Source: NOAA CPC, Climate Prediction Center (2026).

Subsurface temperature anomalies

Figure. Subsurface temperature anomalies (°C) relative to the 1991–2020 climatology. Source: NOAA CPC, Climate Prediction Center (2026). Cross-section of the tropical basin, along the equator, showing the evolution of subsurface temperature anomalies over time. The vertical axis represents depth (in meters), while the horizontal axis represents longitude (in degrees). Positive anomalies indicate warmer-than-average conditions, while negative anomalies indicate cooler-than-average conditions.

Convective activity and precipitation

Latest OLR anomalies, negative values indicate enhanced convection and precipitation, while positive values indicate suppressed convection and precipitation.

Figure. Outgoing longwave radiation (OLR) anomalies. Negative values indicate enhanced convection and precipitation, while positive values indicate suppressed convection and precipitation. Source: NOAA PSL, NOAA Physical Sciences Laboratory (2026).

Animations focused on the Atlantic Ocean are available from NOAA CPC, Climate Prediction Center (2026).

–> An example for the 31-day SST average

References

Climate Prediction Center. 2026. Climate Prediction Center Contacts. National Centers for Environmental Prediction, National Weather Service, NOAA. https://cpc.ncep.noaa.gov/information/personnel/contacts.shtml.
NOAA Physical Sciences Laboratory. 2026. Data/Image Provided by the NOAA/OAR/PSL, Boulder, Colorado, USA, from Their Web Site at Https://Psl.noaa.gov/. National Oceanic; Atmospheric Administration (NOAA). https://psl.noaa.gov/disclaimer/.
Worou, Koffi, Hugues Goosse, Thierry Fichefet, Françoise Guichard, and Moussa Diakhate. 2020. “Interannual Variability of Rainfall in the Guinean Coast Region and Its Links with Sea Surface Temperature Changes over the Twentieth Century for the Different Seasons.” Climate Dynamics 55 (3-4): 449–70. https://doi.org/10.1007/s00382-020-05276-5.