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Cook Islands Meteorological Service

Early Action Rainfall Watch

The Early Action Rainfall Watch provides sector managers with a brief summary of recent rainfall patterns, particularly drought and the rainfall outlook for the coming months.

ENSO Status - Latest

Current El Niño-Southern Oscillation (ENSO) status:

The ENSO Outlook remains at El Niño WATCH. This means that while the El Niño–Southern Oscillation (ENSO) is currently neutral, there is approximately a 50% chance of El Niño developing in 2023. This is about twice the normal likelihood.

All climate models surveyed by the Bureau suggest that oceanic El Niño thresholds are likely to be approached or exceeded during the southern hemisphere winter.

Cook Islands Meteorological Services along with regional climate partners will continue to closely monitor conditions in the tropical Pacific as well as model outlooks for further developments.

Status summary:

Very Dry and Seriously Dry conditions exist over the north-east Cook Islands on the 1-month timescale. At the 3-, 6- and 12-month timescales, Northern Cook Islands is in Seriously Dry (Meteorological Drought) conditions.

It appears that Seriously Dry conditions over the Northern Cook Islands have recently started to ease.

Outlook summary: For May, There is a Medium chance of Very Wet conditions over most of the Northern Cook Islands, increasing to a High chance over Suwarrow. There is a medium chance of Very Dry conditions over parts of the Southern Cook Islands, including over Palmerston.

For May to July 2023, There is a Medium chance of Very Dry conditions for northern parts of the Southern Cook Islands.


The outlook suggests Very Dry conditions may develop again over the Northern Cook Islands from June 2023 onwards.

See table/maps below for additional information. See status table below for potential impacts.


After the specified period of below or above average rainfall, the following primary agricultural and hydrological variables and secondary socio-economic and health variables may be impacted. Note the periods are estimates only. Allow for uncertainty associated with island size, topography, and geology and soil type. Contact the relevant sector offices for further information on impacts.



Rainfall monitoring for 12-month, 6-month, 3-month and the past month



rainfall maps

About Rainfall Monitoring

The Standardized Precipitation Index (SPI) is used to assess rainfall status from the MSWEP dataset. MSWEP is a global precipitation product that combines rain gauges, satellite and reanalysis data to a 0.1° resolution. Meteorological Drought is defined as drought assessed by rainfall data only. A site is assigned 'No Alert' when rainfall has been near normal for the period(s) in question. The 3-, 6- and 12-month timescales can accurately predict drought, whereas 1-month status is an approximation only. This is because it is difficult to assess drought at this timescale.


Extreme Rainfall Outlooks


Rainfall Outlooks for December 2022, and December to February 2023

Outlook Maps


About Rainfall Outlook

Seasonal outlooks have been produced using the Australian Bureau of Meteorology ACCESS-S model The outlook provides an indication of total one and three-month rainfall, not how intense the rain may be in any one event, nor how it may vary within the three months. A station is assigned 'No Alert' when near normal rainfall is favoured or there are equal chances of below normal, normal and above normal rainfall.


Contact the Cook Islands Meteorological Service for further information

The Director, Cook Islands Meteorological Service

P.O Box 127, Rarotonga, Cook Islands, Phone: 682 20603,

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