Island Climate Update 269 - March 2023

The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of February was -0.47˚C, in neutral territory for the first time since July-August 2022.

The SOI was +0.9 during February and +1.2 over the December-February period, the latter still in the La Niña range.

Trade winds were stronger than normal during February in the equatorial Pacific, although significantly reduced trade winds and a westerly wind burst are predicted for March. This will cause sea surface temperatures to increase.

In the subsurface central equatorial Pacific, La Niña’s decay continued during February. Sub-surface water temperatures were above average across the entire basin, with waters in the upper 100 m of the eastern equatorial Pacific becoming more anomalously warm as compared to January.

NIWA’s analysis indicates that La Niña conditions will transition to ENSO-neutral during March-May, most likely during March (95% chance). During June-August, El Niño is favoured at around a 60% chance. The chance for El Niño remains around 60% from September-December 2023. The potential for El Niño conditions by the end of the year is also supported by trends in sub-surface ocean conditions and trade winds.

A pulse of the Madden-Julian Oscillation (MJO) was active over the Pacific Ocean during early March and will progress toward the Americas in the mid-month. This may be associated with additional tropical cyclone formation in the Southwest Pacific through mid-March.

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Island Climate Update March 2023 (PDF 5 MB)