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Island Climate Update

A monthly summary of the climate in the tropical South Pacific islands, with an outlook for the coming months.

November 2026 - January 2027 Island Climate Update

The current El Nino has now reached very strong status and continues to strengthen. There is a 100% chance that El Nino will continue during November 2026-January 2027, and a 100% chance that El Nino will continue during December 2026-February 2027. This El Nino may become the strongest El Nino on record.

As of 12 October 2026, the 30-day NINO3.4 Index (in the central equatorial Pacific) was 3.16˚C, in very strong El Nino range. The 30-day relative Nino 3.4 Index (RONI) was 2.38˚C, in very strong El Nino range and reflective of the central equatorial Pacific being warmer than the average of the global tropics.

The Southern Oscillation Index (SOI) was in strong El Nino range during July-September 2026 (-2.3), while the September value was -2.2.

Subsurface ocean temperatures in the equatorial Pacific continue to be well above average in the eastern part of the basin, and upper-ocean heat content anomalies are well above average in the tropical eastern Pacific.

Extremely warm water continues to be located in the eastern equatorial Pacific from the surface to depths of about 150 metres, where temperature anomalies of 6-8°C are widespread, and reach 10°C in some places. This indicates that a very strong El Nino is now occurring, and further strengthening to record levels is possible by late 2026.

During November 2026-January 2027, model guidance favours above normal or well above normal rainfall for several island groups along the equator, including Naoero, Kiribati, northern Tuvalu, Tokelau, the northern Cook Islands, and the Marquesas.

Conversely, below normal or well below normal rainfall is likely to occur for many island groups in the Pacific, including nearly all of Micronesia and those along a line from Papua New Guinea east to the Pitcairn Islands. Most of these island groups will also have a high chance to be extremely dry during November-January (i.e. seasonal rainfall totals below the 25th percentile). See pages 6-7 for more information.

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Additional resources

Additional regional and country situation summary and forecast information can be obtained below. Current rainfall accumulation status and other derived summary information are updated on a daily basis (with a 2-day lag), with seasonal forecast information updated once per month.

About the Island Climate Update

NIWA is the Network co-lead for the WMO RA V Regional Climate Centre Node on Long Range Forecast and consortium member for nodes on Climate Monitoring, Operational Data Services and Training.

Development and production of the ICU is supported by NIWA Strategic Science Investment Funding under contract PRAS2301. The Island Climate Update bulletin and associated video and products are prepared as soon as possible at the start of each month. Delays in data availability occasionally arise. While every effort is made to verify the data, NIWA does not guarantee the accuracy and reliability of the analysis and forecast information presented and accepts no liability for any losses incurred through the use of this bulletin and its contents. The contents of this bulletin and all associated products produced by the Island Climate Update may be freely disseminated provided the source is acknowledged.

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View past monthly Island Climate Update issues (2001 to present) here Island Climate Update | NIWA

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