Island Climate Update 267 - January 2023

The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was -0.83˚C (climatology: 1991-2020), showing a slight warming trend compared to November.

The SOI was +1.7 during December and +1.3 over the October-December period (climatology: 1991-2020), both within the La Niña range.

Trade winds were stronger than normal during December, sustaining oceanic La Niña conditions. However, In the subsurface central equatorial Pacific, substantial changes took place during December as warmth associated with the West Pacific Warm Pool shifted eastward.

Cooler than average waters contracted toward the central part of the basin while warmer than average waters at depth pushed from the central to the east. This was reflective of a decaying La Niña. Any substantial relaxation or reversal in trade winds over the next three months will move the system toward ENSO neutral.

NIWA’s analysis indicates that La Niña conditions are most likely to transition to ENSO-neutral during January-March, most likely later in the period (65% chance). During April-June, ENSO-neutral is favoured at a 65% chance. The chance for El Niño increases to around 65% from July-September 2023. The last time El Niño conditions occurred during that time of the year was in 2015.

A pulse of the Madden-Julian Oscillation will move across the Pacific during January, coinciding with an increase in the odds for tropical cyclone activity during the 2nd and 3rd week of the month. This is a remainder for all to remain vigilant and keep up to date with your local meteorological service.

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Island Climate Update - January 2023 [PDF 5.8 MB]