When this index is positive, it indicates that the Walker circulation is amped up. One measure of the atmospheric component of ENSO is the Equatorial Southern Oscillation Index (EQSOI), which measures the relationship between surface air pressure in the western and eastern Pacific. However, without the cooler sea surface characteristic of La Niña, it’s likely this pattern will diminish in the coming weeks. The atmosphere is a little more complicated, as it tends to be! We still see some indications of a La Niña-like strengthened Walker circulation, with more rain and clouds than average over Indonesia, less over the central Pacific, and enhanced trade winds.

Description of historical baseline period.

Graphic by, based on data from NOAA’s Environmental Visualization Lab. East of the International Dateline (180˚), waters remained cooler than average, a sign of La Niña. Sea surface temperatures in the tropical Pacific Ocean from early January through early March 2023 compared to the long-term average.

Surface latest