Island Climate Update

A monthly summary of the climate in the tropical South Pacific islands, with an outlook for the coming months. This bulletin is a multi-national project with collaboration from a number of Pacific nations and support from various organisations.

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Issues

The NINO3.4 Index anomaly (in the central Pacific) during September was -0.23˚C. Compared to this time last year, conditions are about 0.5˚C warmer. The Southern Oscillation Index (SOI) was +0.8 during September, on the La Niña side of neutral. Notably, the three-month average SOI was +1.0, in La Niña territory.
The NINO3.4 Index anomaly (in the central Pacific) during August was -0.17 ̊C. The Southern Oscillation Index was +0.5. While both remained in neutral territory, other indicators trended toward La Niña.
The NINO3.4 Index anomaly (in the central Pacific) during July was 0.08 ̊C. The Southern Oscillation Index was +1.7, firmly in La Niña territory.
The NINO3.4 Index anomaly (in the central Pacific) during June was 0.18 ̊C, the first time it has been positive since July 2020. The Southern Oscillation Index was +0.4, in the ENSO neutral range.
The NINO3.4 Index anomaly (in the central Pacific) during May (through the 30th) was -0.11˚C, the smallest anomaly since July 2020. The Southern Oscillation Index (SOI) was +0.5, in the ENSO neutral range.
The NINO3.4 Index anomaly (in the central Pacific) during April was -0.30⁰C and the SOI (Southern Oscillation Index) was +0.3, both within the neutral range.
The NINO3.4 Index anomaly (in the central Pacific) during March was -0.44˚C. This marked the first time since August 2020 that SSTs in this region were in the neutral range. The SOI value for March was +0.1 (in the neutral range).
The NINO3.4 Index anomaly (in the central Pacific) during January was -0.68˚C, entering ENSO “cool neutral” territory (-0.5 to -0.69˚C) for the first time since August 2020.
The NINO3.4 Index anomaly (in the central Pacific) during January was 0.81˚C, increasing slightly compared to the previous month.
The NINO3.4 Index anomaly (in the central Pacific) for the last month (through the 3 rd of January) was 0.84˚C, increasing from 1.03˚C from last month.
During November, the NINO3.4 Index anomaly (central Pacific) was 1.02˚C. The NINO 1+2 Index (eastern Pacific) was 0.54 C. The most unusually cool SSTs have now shifted into the central Pacific.
During October, the NINO3.4 Index anomaly (central Pacific) was 0.86˚C. The NINO 1+2 Index (eastern Pacific) was 0.56 C. Upper oceanic heat content continued to decrease in the east central part of the Pacific basin.
During September, the NINO3.4 Index anomaly (central Pacific) was 0.71˚C. The NINO 1+2 Index (eastern Pacific) was 0.76 C.
During August, the NINO3.4 Index anomaly (in the central Pacific) was 0.42˚ C. The NINO 1+2 Index (eastern Pacific) was 0.85 C.
During July, the NINO3.4 Index anomaly (in the central Pacific) was +0.04˚C. The NINO 1+2 Index (eastern Pacific) was 0.72 C, decreasing from 0.57 C in June.
During June, the NINO3.4 Index anomaly (in the central Pacific) was 0.12˚C. Upper oceanic heat content decreased notably across the east central equatorial Pacific.
During May the NINO3.4 Index anomaly (in the central Pacific) for May was +0.01˚C, with upper oceanic heat content continuing to decrease across the equatorial Pacific.
El Niño Southern Oscillation (ENSO) neutral conditions continued during April 2020. The Southern Oscillation Index (SOI) was +0.1.
El Niño Southern Oscillation (ENSO) neutral conditions continued during March 2020. The Southern Oscillation Index (SOI) was 0.5.
El Niño Southern Oscillation (ENSO) neutral conditions continued during February 2020. The Southern Oscillation Index (SOI) was 0.2.
El Niño-Southern Oscillation (ENSO) neutral conditions continued during January 2020. The Southern Oscillation Index (SOI) was +0.2, the first positive monthly value since December 2018.
El Nino –Southern Oscillation (ENSO) neutral conditions continued during December 2019. Both the Southern Oscillation Index (SOI) and sea surface temperatures (SSTs) remained on the El Niño side of neutral but weakened compared to previous months.
ENSO-neutral conditions continued during November 2019, although the Southern Oscillation Index (SOI) dipped into El Niño territory and sea surface temperatures (SSTs) were on the El Niño side of neutral.
ENSO-neutral conditions continued during October 2019, although the Southern Oscillation Index (SOI) and sea surface temperatures (SSTs) were on the El Niño side of neutral.

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