Island Climate Update

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

April-June 2024 Island Climate Update

El Niño has continued to weaken during May, and ENSO neutral conditions are favoured to develop by June 2024.

The 30-day NINO3.4 Index anomaly (in the central equatorial Pacific) as of 20 May was +0.49˚C, falling below the El Niño threshold of +0.7˚C.

The 30-day Niño 1+2 Index anomaly was -0.22˚C, within the neutral range. In fact, it is the lowest value in that region since February 2023, at the end of the last La Niña event.

The Southern Oscillation Index (SOI) was in the neutral range during March-May (+0.2), but the May value was +0.7 (in the La Niña range).

Periods of enhanced trade winds in the coming months should contribute to additional cooling of sea-surface temperatures near the equator.

During mid-May, the subsurface equatorial Pacific was 4˚C to 6˚C cooler than average just below the surface in the east of the basin.

Meanwhile, above average temperatures persisted in the central and western parts of the basin. This signature was reflective of an oceanic transition out of El Niño toward a possible La Niña in a few months.

The South Pacific Convergence Zone was near its climatological normal position during May.

During the first half of June, a pulse of the Madden-Julian Oscillation may propagate across the Pacific. This may lead to a period of heavy rainfall with the potential for flooding, especially south of the equator in the South Pacific, like what’s shown on page 6 (June outlook).

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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

Issues

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    Island Climate Update 284 - June 2024

    El Niño has continued to weaken during May, and ENSO neutral conditions are favoured to develop by June 2024.
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    Island Climate Update 283 - May 2024

    El Niño continued to weaken during April, and ENSO neutral conditions are favoured to develop by June 2024.
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    Island Climate Update 282 - April 2024

    El Niño continued during March but continues to weaken. ENSO neutral conditions are favoured to develop by June 2024.
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    Island Climate Update 281 - March 2024

    The El Niño event is now past its peak oceanic intensity and it is likely to weaken further during March.
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    Island Climate Update 280 - February 2024

    El Niño was active during January and will very likely continue over the next three months.
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    Island Climate Update 279 - January 2024

    El Niño continued during December and has around a 100% chance of persisting through March.
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    Island Climate Update 278 - December 2023

    El Niño continued during November and will likely remain in place during the next three months.
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    Island Climate Update 277 - November 2023

    El Niño continued during October and will likely intensify during the next three months.
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    Island Climate Update 276 - October 2023

    El Niño has officially arrived. A majority of NIWA’s criteria for classifying an El Niño event were satisfied during September.
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    Island Climate Update 275 - September 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of August was +1.34˚C. The weekly value reached +1.5˚C at the end of the month – the traditional threshold for a strong oceanic El Niño.
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    Island Climate Update 274 - August 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of July was 1.11 ˚C . At the same point during the developmental phase of strong past El Niño events , it was +1.35˚C in 2015, +1.31˚C in 1997, and +0.26˚C in 1982.
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    Island Climate Update 273 - July 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of June was +0.93˚C. This is warmer than it was at the same time during the development of strong El Niño events in 1997 and 1982.
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    Island Climate Update 272 - June 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of May was 0.49˚C, an increase of nearly 0.3˚C from April and trending toward NIWA’s El Niño threshold of 0.7˚C.
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    Island Climate Update 271 - May 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the beginning of May was 0.21˚C, in the neutral range, but gradually warming.
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    Island Climate Update 270 - April 2023

    The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of March was -0.01˚C, in the neutral range for the second consecutive month.
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    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.
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    Island Climate Update 268 - February 2023

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was -0.69˚C, close to La Niña thresholds.
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    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.
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    Island Climate Update 266 - December 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was 0.92˚C (climatology: 1991 2020), showing a cooling trend compared to October.
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    Island Climate Update 265 - November 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was -0.80˚C (climatology: 1991-2020), in the La Niña range for the third consecutive month.
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    Island Climate Update 265 - October 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month (through 30 September) was -0.93˚C (climatology: 1991-2020). In the last four decades, only four Septembers hadcooler central equatorial Pacific SSTs than 2022, including September 2010, 1999, 1998, and 1988.
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    Island Climate Update 264 - September 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month (through 31 August) was -1.00˚C (climatology: 1991-2020), showing a strong cooling trend compared to July. In the last four decades, only four Augusts had cooler central equatorial Pacific SSTs than 2022, including August 2010, 1999, 1998, and 1988.
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    Island Climate Update 263 - August 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month (through 31 July) was -0.34˚C (climatology: 1961-1990); the latest weekly anomaly was -0.43˚C, showing a late-month cooling trend.
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    Island Climate Update 262 - July 2022

    The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was -0.40˚C, in the “cool-neutral range”. The three-monthly NINO3.4 Index remained near the La Niña threshold.