Last update: February 25, 2019, 6:08 EST
Description
The Niño 3.4 index is one of several El Niño/Southern Oscillation (ENSO) indicators based on sea surface temperatures. Click here to see the latest ENSO statements.
Niño 3.4 index is the average sea surface temperature (SSTs) anomaly in the region bounded by 5°S to 5°N latitude and 170°W to 120°W longitude. This region has large variability on El Niño time scales, and is close to the region where changes in local sea-surface temperature are important for shifting the large region of rainfall typically located in the far western Pacific. The Niño 3.4 anomalies may be thought of as representing the average equatorial SSTs across the Pacific from about the dateline to the South American coast. The Niño 3.4 index typically uses a 3-month running mean, and El Niño or La Niña events are defined when the Niño 3.4 SSTs exceed +/- 0.5C for a period of six months or more.
Updated weekly
Source: NOAA National Weather Service / Climate Prediction Center, The Australian Bureau of Meteorology