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The Island Climate Update

El Niño/Southern Oscillation (ENSO)

  • Moderate La Niña conditions continued in the equatorial Pacific during December, but a weakening trend was noted.
  • Both sea surface temperatures (SSTs) and the Southern Oscillation Index (SOI) were in the La Niña range.
  • Warmth in the equatorial Pacific sub-surface ocean spread eastward during December, signaling the start of La Niña’s decay.
  • 65% chance for ENSO-neutral conditions to develop during January – March 2023.
  • 65% Chance for ENSO Neutral conditions during April-June 2023

Water Stress Outlook

January 2023 forecast summary
  • During January, there continues to be a high chance for drier than normal conditions along and extending southeastward of the equator, including most island groups that recently experienced dryness. Notably, this includes Samoa, American Samoa, and Tuamotu, which had low or very low rainfall during December.
  • Water stress is forecast to persist in far southern FSM, far northern PNG, Nauru, parts of Kiribati, and Tuamotu.
  • Water stress may redevelop in parts of Tuvalu and the Northern Cook Islands.
  • Water stress may ease in the Marshall Islands, the Solomons, Society Islands, and the Pitcairn Islands.
January – March 2023 forecast summary
  • During January-March, there is a high chance for drier than normal conditions in island groups along and south-east of the equator.
  • The three-month outlook looks very similar to the one issued this time last month, but the odds for dryness aren’t quite as high for southern FSM, PNG, Solomons, Nauru, and parts of Kiribati.
  • Seasonal water stress is most likely to persist in a narrow strip near and extending south-east of the equator but shows signs of gradually easing elsewhere.
  • La Niña’s influence on rainfall patterns will continue for a portion of this period but may become less pronounced toward March as the system moves toward ENSO-neutral.