El Niño and La Niña | NIWA
El Niño and La Niña are opposite phases of a naturally occurring global climate cycle known as the El Niño Southern Oscillation, or ENSO for short.
El Niño and La Niña \| NIWA[Skip to main content](#main-content)

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## Primary menu

- [Atmosphere](/atmosphere "World class research contributing to our understanding of greenhouse gases, ozone depletion, and urban air pollution.")










# Atmosphere











World class research contributing to our understanding of greenhouse gases, ozone depletion, and urban air pollution.









[Explore all](/atmosphere)

















































[Air quality](/atmosphere/air-quality)



[Greenhouse and trace gases](/atmosphere/greenhouse-and-trace-gases)



[UV and ozone](/atmosphere/uv-and-ozone-1)























## [Research](https://niwa.co.nz/atmosphere?pt=10\#filters)





[CarbonWatch NZ](/climate/research-projects/carbon-watch-nz)



[MethaneSAT](/atmosphere/methanesat)



[Total Carbon Column Observing Network](/atmosphere/research-projects/total-carbon-column-observing-network)



[Chemistry-climate modelling](/atmosphere/chemistry-climate-modelling)



[Community Air](/atmosphere/community-air-air-quality-issues-nz-towns)



[Post-cyclone air quality](/atmosphere/air-quality/assessing-post-cyclone-air-quality-across-tairawhiti-and-hawkes-bay)



[Ventilation and Covid-19 transmission](/atmosphere/research-projects/reducing-covid-19-transmission-through-increased-ventilation)



[Traffic emissions - mapping air quality](/atmosphere/research-projects/traffic-emissions-mapping-black-carbon-and-nitrogen-dioxide)













## [Tools & services](https://niwa.co.nz/atmosphere?pt=13\#filters)





[Trace gas datasets](/atmosphere/our-data/trace-gas-datasets)



[Carbon dioxide data](/atmosphere/carbon-dioxide)



[Methane data](/atmosphere/methane)



[Air quality monitoring with low-cost sensors](/atmosphere/services-and-data/air-quality-monitoring-with-low-cost-sensors)



[UV & ozone](/atmosphere/uv-and-ozone)













## [Facilities](https://niwa.co.nz/atmosphere?pt=6\#filters)





[Baring Head Atmospheric Research Station](/atmosphere/facilities/baring-head)



[Lauder Atmospheric Research Station](/atmosphere/facilities/lauder-atmospheric-research-station)





























[Link to source page](/atmosphere/methanesat)





![MethaneSAT Mission](/sites/default/files/styles/card_mega_menu/public/2023-12/MethaneSATMission_web.jpg?h=094f39d6&itok=En9ShN2s)





## MethaneSAT





Research Project



10 May 2023



Detecting and quantifying methane emissions by satellite

- [Climate & Weather](/climate-and-weather "Understanding our variable and changing climate is critical for managing resources and reducing risks.")










# Climate & Weather











Understanding our variable and changing climate is critical for managing resources and reducing risks.









[Explore all](/climate-and-weather)

















































[Climate change](/climate-and-weather/climate-change)



[Climate change adaptation](/climate-and-weather/climate-change-adaptation)



[Climate data](/climate-and-weather/climate-data)



[Climate modelling and projections](/climate-and-weather/climate-modelling-and-projections)



[Weather forecasting](/climate-and-weather/weather-forecasting)



[Renewable energy](/renewable-energy)























## [Research](https://niwa.co.nz/climate-and-weather?pt=10\#filters)





[Updated national climate projections](/climate/research-projects/updated-national-climate-projections-for-aotearoa-new-zealand)



[Physics + AI climate projections](/climate/research-projects/physics-and-ai-based-high-resolution-climate-projections)



[Nowcasting for solar and wind](/climate-and-weather/nowcasting-and-short-medium-range-forecasting-solar-and-wind-energy)



[Climate present and past](/climate/research-projects/climate-present-and-past)



[Providing climate change advice for NZ](/climate/research-projects/providing-climate-change-advice-to-new-zealands-regions)



[Forecasting weather systems](/climate-and-weather/forecasting-weather-systems)



[Citizen science - rainfall monitoring](/climate/information-and-resources/citizen-science-new-zealand-rainfall-monitoring-network)



[Serious games as a tool to engage people](/climate-and-weather/serious-games-tool-engage-people)













## [Tools & services](https://niwa.co.nz/climate-and-weather?pt=13\#filters)





[Climate change adaptation toolbox](/climate-and-weather/climate-change-adaptation-toolbox)



[Weather and climate forecasting services](/climate-and-weather/weather-and-climate-forecasting-services)



[Drought forecasting dashboard](https://shiny.niwa.co.nz/drought-forecast/)



[Leveraging updated climate projections](/climate-and-weather/niwa-can-help-you-leverage-updated-climate-projections)



[Climate data](/climate/our-services/obtaining-climate-data-from-niwa)



[Virtual Climate Stations](/climate/our-services/virtual-climate-stations)



[Climate mapping](/climate/our-services/climate-mapping)



[Daily climate maps](/climate-and-weather/daily-climate-maps)













## [Understanding our climate](https://niwa.co.nz/climate-and-weather?pt=All&sort_by=recent\#filters)





[Seasonal climate outlooks](/seasonal-climate-outlook/seasonal-climate-outlook)



[Climate summaries](/climate-and-weather/climate-summaries-0)



[Sea Surface Temperature Update](/climate-and-weather/sea-surface-temperature-update)



[Regional climatologies](/climate-and-weather/regional-climatologies)



[Southwest Pacific Tropical Cyclone Outlook](/rainfall/southwest-pacific-tropical-cyclone-outlook)



[Island Climate Update](/climate-and-weather/island-climate-update)



[El Niño and La Niña](/el-nino-and-la-nina)



[NZ temperature record](/climate/information-and-resources/nz-temperature-record)





























[Link to source page](/climate-and-weather/niwa-can-help-you-leverage-updated-climate-projections)





![](/sites/default/files/styles/card_mega_menu/public/2022_PHOTO_COMP_Skyline_Hookcropped.jpg?h=034a5371&itok=5geu_pYl)





## NIWA can help you leverage updated climate projections





Service



29 August 2024



NIWA is using updated climate projections to help New Zealanders better understand climate-related risks.

- [Hazards](/hazards "Nature can be a destructive force. Our science prevents property damage and saves lives.")










# Hazards











Nature can be a destructive force. Our science prevents property damage and saves lives.









[Explore all](/hazards)





















[Coastal hazards](/hazards/coastal-hazards)































[Weather hazards](/hazards/weather-hazards)



[Geological hazards](/hazards/geological-hazards)























## [Research](https://niwa.co.nz/hazards?pt=10)





[Future Coasts Aotearoa](/hazards/future-coasts-aotearoa)



[Identifying rip currents using AI](/hazards/identifying-rip-currents-using-artificial-intelligence)



[Riskscape software](/hazards/riskscape-software)



[Mā te haumaru ō te wai: Aotearoa flood resilience](/hazards/ma-te-haumaru-o-nga-puna-wai-o-rakaihautu-ka-ora-mo-ake-tonu-increasing-flood)



[Responding to and preparing for extreme weather events](/hazards/research-projects/responding-to-and-preparing-for-extreme-weather-events)



[Forecasting weather systems](/climate-and-weather/forecasting-weather-systems)



[Tsunami generated by underwater volcanoes](/hazards/tsunami-generated-underwater-volcanoes)



[River flow forecasting](/hazards/weather-hazards/river-flow-forecasting)













## [Tools & services](https://niwa.co.nz/our-services?subtree%5Btopic%5D=198)





[Extreme coastal flood maps for Aotearoa New Zealand](/hazards/coastal-hazards/extreme-coastal-flood-maps-aotearoa-new-zealand)



[Storm-tide red-alert days 2024](/coasts/physical-hazards-affecting-coastal-margins-and-continental-shelf/storm-tide-red-alert-days-2024)



[Tide forecaster](/coasts/tide-forecaster)



[Sea levels and sea-level rise](/hazards/coastal-hazards/sea-levels-and-sea-level-rise)



[Drought dashboard](https://shiny.niwa.co.nz/drought-forecast/)



[Serious games as a tool to engage people](/climate-and-weather/serious-games-tool-engage-people)

























[Link to source page](/news/tonga-eruption-confirmed-largest-ever-recorded)





![](/sites/default/files/styles/card_mega_menu/public/2022_10_3D_MODEL_HTHH_parsonskingDSC00900-web.jpg?h=f3f0a9e5&itok=gsi2rTI3)





## Tonga eruption confirmed as largest ever recorded





Media release



21 November 2022



A New Zealand-led team has completed the fullest investigation to date into January’s eruption of the underwater Tongan volcano.

- [Coasts & Oceans](/coasts-and-oceans "NIWA aims to provide the knowledge needed for the sound environmental management of our marine resources.")










# Coasts & Oceans











NIWA aims to provide the knowledge needed for the sound environmental management of our marine resources.









[Explore all](/coasts-and-oceans)

















































[Fisheries](/fisheries)



[Aquaculture](/aquaculture)



[Oceans](/oceans)



[Coasts](/coasts)



[Estuaries](/coasts/estuaries)



[Antarctica](/antarctica)























## [Research](https://niwa.co.nz/research)





[Antarctica](/antarctica?pt=10#filters)



[Aquaculture](/aquaculture?pt=10#filters)



[Coasts](/coasts?pt=10#filters)



[Estuaries](/research?subtree%5Btopic%5D=6145&subtree%5Bsubtopic%5D=158&created=All)



[Fisheries](/fisheries?pt=10#filters)



[Oceans](/oceans?pt=10#filters)













## [Tools & Services](https://niwa.co.nz/our-services)





[Aquaculture](/aquaculture?pt=13#filters)



[Coasts](/coasts?pt=13#filters)



[Estuaries](/our-services?subtree%5Btopic%5D=6145&subtree%5Bsubtopic%5D=158)



[Fisheries](/fisheries?pt=13#filters)



[Oceans](/oceans?pt=13#filters)



[NIWA Vessels](/vessels/niwa-vessels)













## [Frequently visited](https://niwa.co.nz/coasts-and-oceans?pt=27)





[Kingfish aquaculture](/aquaculture/yellowtail-kingfish)



[Future Coasts Aotearoa](/node/113711)



[Marine biosecurity](/coasts/marine-biosecurity)



[The Ross Sea toothfish fishery](/fisheries/ross-sea-toothfish-fishery)



[Recreational Fishing](/fisheries/recreational-fishing)



[Marine identification guides](/coasts/marine-identification-guides-and-fact-sheets)



[Voyages](/vessels/voyages)



[eDNA research and services](/coasts/edna-research-and-services)

























[Link to source page](/news/open-wide-snapper-teeth-secrets)





![Snapper](/sites/default/files/styles/card_mega_menu/public/2023-05/snapper.jpg?h=9396f34a&itok=8pFBdBte)





## Open wide: snapper teeth secrets





News article



12 May 2023



NIWA and University of Auckland masters student Georgia Third is getting up close and personal with snapper guts and teeth to understand the differences between biologically distinct snapper populations in New Zealand.

- [Freshwater](/freshwater "We provide public information on river, lake, and groundwater conditions across New Zealand including water quantity and quality.")










# Freshwater











We provide public information on river, lake, and groundwater conditions across New Zealand including water quantity and quality.









[Explore all](/freshwater)

















































[Ecological monitoring](/freshwater/ecological-monitoring)



[Ecotoxicology](/freshwater/ecotoxicology)



[Freshwater fish](/freshwater/freshwater-fish)



[Freshwater invertebrates](/freshwater/freshwater-invertebrates)



[Freshwater quality](/freshwater/freshwater-quality)



[Freshwater restoration](/freshwater/freshwater-restoration)























## [Research](https://niwa.co.nz/freshwater?pt=10)





[Investigating ecological impacts on freshwater insects from LED streetlights](/freshwater/research-projects/investigating-ecological-impacts-on-freshwater-insects-from-led-streetlight-conversions)



[Effective mitigation systems to manage contaminant losses](/freshwater/research-projects/effective-mitigation-systems-to-manage-contaminant-losses)



[Cultural Keystone Species](/te-kuwaha/research-projects/cultural-keystone-species-co-management-and-restoration-of-our-freshwater-taonga-species)



[Freshwater bioremediation using native mussels](/freshwater/research-projects/freshwater-bioremediation-using-native-mussels-focussed-on-shallow-eutrophic-lakes)



[Hauraki Integrated Land-Water Modelling](/freshwater/research-projects/hauraki-integrated-land-water-modelling)



[Snow and Ice Network](/freshwater/research-projects/snow-and-ice-network)













## [Services](https://niwa.co.nz/freshwater?pt=13)





[Climate change freshwater impacts assessments](/freshwater/our-services/climate-change-freshwater-impacts-assessments)



[Specialist analytical services](/our-science/freshwater/our-services/specialist-analytical-services)



[Flow assessment and management](/freshwater/our-services/flow-assessment-and-management)



[Freshwater databases online](/freshwater/our-services/freshwater-data-online)



[Freshwater species and habitat management](/freshwater/our-services/freshwater-species-and-habitat-management)



[Stormwater management](/freshwater/our-services/stormwater-management)



[Catchment modelling](/freshwater/our-services/catchment-modelling)



[Water quality monitoring and advice](/freshwater/our-services/water-quality-monitoring-and-advice)













## [Tools & Resources](https://niwa.co.nz/freshwater?pt=13)





[Riparian Buffer Design Guide](/freshwater/management-tools/riparian-buffer-design-guide)



[Constructed wetland guidelines](/freshwater/management-tools/restoration-tools/constructed-wetland-guidelines)



[The New Zealand Water Model (NZWaM)](/freshwater/freshwater-update/freshwater-update-80-march-2019/the-new-zealand-water-model-nzwam-%E2%80%93-a-new-water-modelling-approach)



[Biosecurity tools](/freshwater/tools/biosecurity)



[Environmental flow tools](/freshwater/management-tools/environmental-flow-tools)



[Fish Passage Assessment Tool](/freshwater/management-tools/fish-passage-assessment-tool)



[New Zealand streamflow depletion model](/freshwater/management-tools/environmental-flow-tools/new-zealand-streamflow-depletion-model)



[CLUES – Catchment Land Use for Environmental Sustainability model](/freshwater/our-services/catchment-modelling/clues-catchment-land-use-for-environmental-sustainability-model)













## [Programmes](https://niwa.co.nz/freshwater/freshwater-programme-overview)





[Freshwater species ecology and management](/freshwater/programme-overview/freshwater-species-ecology-and-management)



[Hydrological observations and predictions](/freshwater/programme-overview/Hydrological-observations-and-predictions)



[Environmental flows](/freshwater/programme-overview/environmental-flows)



[Causes and effects of water quality degradation](/freshwater/programme-overview/causes-and-effects-of-water-quality-degradation)



[Freshwater biosecurity](/freshwater-biosecurity)



[Mitigation systems](/freshwater/programme-overview/mitigation-systems)





























[Link to source page](/freshwater/freshwater-invertebrate-identification-and-e-guides)





![Image of mayflies [from NIWA Benthic Macroinvertebrates Field Identification Guide]](/sites/default/files/styles/card_mega_menu/public/2023-02/Mayfly-image-NIWA.jpg?h=999433cf&itok=sCEv1D1n)





## Freshwater invertebrate identification and e-guides





Education Resource



06 February 2023



Downloadable and printable guides on identification of common freshwater invertebrates found in New Zealand waterways and lakes.

- [Te Kūwaha](/te-kuwaha-and-maori "Working together with hapū, iwi, Māori communities and Māori business to deliver tailored science.")










# Te Kūwaha











Working together with hapū, iwi, Māori communities and Māori business to deliver tailored science.









[Explore all](/te-kuwaha-and-maori)











































[Taonga species](/te-kuwaha-and-maori/taonga-species)





















## [Research](https://niwa.co.nz/te-kuwaha-and-maori?pt=10\#filters)





[Cultural Keystone Species](/te-kuwaha/research-projects/cultural-keystone-species-co-management-and-restoration-of-our-freshwater-taonga-species)



[Maniapoto Cultural Assessment Framework](/te-kuwaha/research-projects/maniapoto-cultural-assessment-framework)



[The impact of non-native marine pests on our takutai moana](/te-k%C5%ABwaha/research-projects/the-impact-of-non-native-marine-pests-on-our-takutai-moana)



[Ngā repo o Maniapoto - Maniapoto wetland inventory](/te-k%C5%ABwaha/research-projects/ng%C4%81-repo-o-maniapoto-maniapoto-wetland-inventory)













## [Tools & Resources](https://niwa.co.nz/te-kuwaha-and-maori?pt=13\#filters)





[Taonga Species Series](/te-kuwaha/tools-and-resources/taonga-species-series)



[Climate Change Vulnerability Assessment (CCVA)](/te-kuwaha/ccva)



[Kaitiaki Tools](/te-kuwaha-and-maori/kaitiaki-tools)



[Trends analysis for selected indicators of Waikato River health](/te-kuwaha/tools-and-resources/trends-analysis-for-selected-indicators-of-waikato-river-health-and-wellbeing-2010-2019)



[Climate and Māori society](/climate/information-and-resources/climate-and-m%C4%81ori-society)





























[Link to source page](/te-kuwaha-and-maori/te-kuwaha-graduate-programme)





![Koru](/sites/default/files/styles/card_mega_menu/public/2023-01/koru.jpg?h=c74750f6&itok=zxI9Rh7E)





## Te Kūwaha Graduate Programme





19 January 2023



NIWA’s Te Kūwaha Graduate Internship programme has been established to help support and create tangible pathways for the next generation of Māori researchers.

- [Pacific](/pacific "We provide applied science and environmental consultancy services to support international development activities, with a particular focus on the Pacific and Asian regions.")










# Pacific











We provide applied science and environmental consultancy services to support international development activities, with a particular focus on the Pacific and Asian regions.









[Explore all](/pacific)

















































[Pacific Rim partnerships](/pacific/pacific-rim-partnerships)























## [Research](https://niwa.co.nz/pacific?pt=10\#filters)





[Pacific Risk Tool for Resilience, Phase 2 (PARTneR-2)](/pacific-rim/research-projects/pacific-risk-tool-for-resilience-phase-2-partner-2)



[Climate Data for the Environment Services Client (CliDEsc)](/pacific-rim/research-projects/climate-data-for-the-environment-services-client-clidesc)



[PARTneR (Pacific Risk Tool for Resilience)](/natural-hazards/research-projects/partner)



[Improved sustainability of the demersal line fishery in Tonga](/pacific/improved-sustainability-demersal-line-fishery-tonga)



[On-Site Household Sanitation Guidelines for Fiji](/pacific-rim/research-projects/koro-sanitation-guidelines)



[Energy assessment for Totoya Island, Fiji](/energy/research-projects/energy-assessment-for-totoya-island-fiji)



[Development of sustainable water supply and treatment systems](/pacific-rim/research-projects/development-of-sustainable-water-supply-and-treatment-systems-for-a-coastal-fijian-village)













## [Services](https://niwa.co.nz/pacific?pt=13\#filters)





[Pacific Rim Services](/our-science/pacific-rim/our-services)



[Improved climate information and services in Vanuatu](/news/improved-climate-information-and-services-in-vanuatu)





























[Link to source page](/fisheries/fisheries-and-ecosystems)





![Snapper](/sites/default/files/styles/card_mega_menu/public/2023-11/20200428_snapper_105_JW.jpg?h=e5aec6c8&itok=To2SqSNX)





## Fisheries & ecosystems





30 January 2023



NIWA will be determining the impact of fisheries on the aquatic environment. This will inform an ecosystem-based approach to fisheries management and the development methods to mitigate this impact.


## Secondary menu

- [About](/about-niwa "Decision makers at all levels are seeking evidence-based analysis and advice from environmental experts. NIWA’s science provides high quality insights to underpin important decisions, and innovative solutions.")










# About











Decision makers at all levels are seeking evidence-based analysis and advice from environmental experts. NIWA’s science provides high quality insights to underpin important decisions, and innovative solutions.









[Explore all](/about-niwa)













## [Our people](https://niwa.co.nz/about-niwa/our-people)





[Our board](/about-niwa/our-people/our-board)



[Executive team](/about-niwa/our-people/our-management/executive-team)



[Science management team](/about-niwa/our-people/our-management/science-management-team)



[Operations management team](/about-niwa/our-people/our-management/operations-management-team)



[Staff search](/node/112602)













## [Careers at NIWA](https://niwa.co.nz/about-niwa/careers-niwa)





[Our work](/about-niwa/careers-niwa/our-work)



[Work-life balance](/about-niwa/careers-niwa/work-life-balance)



[The process](/about-niwa/careers-niwa/process)



[Careers - FAQs](/about-niwa/careers-niwa/careers-faqs)



[Coming from overseas?](/about-niwa/careers-niwa/coming-overseas)













## [About us](https://niwa.co.nz/about-niwa)





[Our company](/about-niwa/our-company)



[Our mission](/our-mission)



[Statement of Core Purpose](/about-niwa/statement-core-purpose)



[Annual reports](/about-niwa/annual-reports)



[Our partners & funders](/about-niwa/our-partners-funders)













## [More about us](https://niwa.co.nz/about-niwa)





[Organisational sustainability charter](/about-niwa/organisational-sustainability)



[NIWA and Kia Toipoto - Closing gender and ethnic pay gaps](/about-niwa/niwa-and-kia-toipoto-closing-gender-and-ethnic-pay-gaps)

- [Contact Us](/contact-us "Contact us for all your enquiries about NIWA")










# Contact Us











Contact us for all your enquiries about NIWA















[Explore all](/contact-us)



















## [Contacts](https://niwa.co.nz/contact-us)





[Contact us for general, media and website enquiries](/contact-us)



[NIWA locations](/node/119)

- [Education](/education-and-training "NIWA is committed to education in New Zealand at all levels.")










# Education











NIWA is committed to education in New Zealand at all levels.















[Explore all](/education-and-training)



















## [Education and information](https://niwa.co.nz/education-and-information)





[Climate change](/climate-and-weather/climate-change-information-climate-solvers)



[Clouds](/climate-and-weather/clouds)



[Common hydrological terms](/atmosphere/common-hydrological-terms)



[Common climate and weather terms](/atmosphere/common-climate-and-weather-terms)



[Drought](/climate-and-weather/drought)



[El Niño and La Niña](/el-nino-and-la-nina)



[Southern Annular Mode](/climate-and-weather/southern-annular-mode)



[Storms and cyclones](/atmosphere/storms-and-cyclones)













## [Resources for teachers – lessons and activities](https://niwa.co.nz/about-niwa/resources-teachers)





[My coastal futures: adapting to climate change](/climate-and-weather/my-coastal-futures-online-game)



[Township flood challenge: adapting to more extreme weather](/township-flood-challenge-game)



[Rangi: understanding weather and climate](/rangi-weather-and-climate-lessons-teachers)



[Air aware: air quality lessons](/air-aware-air-quality-lessons-teachers-and-experiments-curious-kids)



[Estuaries: when fresh water meets salty](/when-fresh-water-meets-salty-water)



[Other climate data and activities](/climate-and-weather/climate-data-and-activities)



[NIWA posters to order](/gallery/niwa-posters)













## [More education](https://niwa.co.nz/education-and-training)





[Science and technology fairs](/about-niwa/science-and-technology-fairs)



[Te Kūwaha Graduate Programme](/te-kuwaha-and-maori/te-kuwaha-graduate-programme)



[Te Piko o te Māhuri](/about-niwa/te-piko-o-te-mahuri)



[Scholarships](/about-niwa/scholarships)



[Supporting postgraduate students](/about-niwa/tertiary-institutions-we-work)



[Post-doctoral fellowships](/about-niwa/post-doctoral-fellowships)



[NIWA training courses](/about-niwa/training-courses)

- [News](/news "Read about the important science being undertaken at NIWA, and how it affects New Zealanders")










# News











Read about the important science being undertaken at NIWA, and how it affects New Zealanders















[Explore all](/news)



















## [News manual links](https://niwa.co.nz/news)











## [Publications](https://niwa.co.nz/publications)





[Water & Atmosphere magazine](/water-atmosphere)















## [News & Events](/news)









[Cyclone Gabrielle was intensified by human-induced global warming](/news/cyclone-gabrielle-was-intensified-human-induced-global-warming)







[New vessel to study undersea in the Hauraki Gulf](/news/new-vessel-study-undersea-hauraki-gulf)







[Water therapy](/about-niwa/water-atmosphere/water-atmosphere-31-july-2024/water-therapy)







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# El Niño and La Niña

El Niño and La Niña are opposite phases of a naturally occurring global climate cycle known as the El Niño Southern Oscillation, or ENSO for short.

[Climate and weather](/climate-and-weather "Climate and weather")

## Breadcrumb

1. [Home](/)
2. El Niño and La Niña


## El Niño Southern Oscillation: what is it?

El Niño and La Niña are opposite phases of a naturally occurring global climate cycle known as the El Niño Southern Oscillation, or ENSO for short. ENSO influences rainfall, temperature, and wind patterns around the world, including New Zealand. El Niño and La Niña episodes occur on average every few years and last up to around a year or two.

Although ENSO has an important influence on New Zealand’s climate, it accounts for less than 25 percent of the year-to-year variance in seasonal rainfall and temperatures at most locations. Nevertheless, its effects can be significant.

[Play video](https://youtu.be/A1r8ymAoe2M)

What is El Niño?

[Watch Video](https://youtu.be/A1r8ymAoe2M)

## **El Niño**

During an El Niño event, ocean water from off the coast of South America (near Ecuador and Peru) to the central tropical Pacific warm above average. The warming takes place as trade winds (the permanent east-to-west prevailing winds that flow around the equator) weaken or even reverse, blowing warm water from the western Pacific toward the east. As a result, sea temperatures in the far western Pacific can cool below average. The unusually warm water in the eastern Pacific then influences the [Walker Circulation](https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy), acting as a focal point for cloud, rainfall, and thunderstorms. It is this change in the Walker Circulation that impacts weather patterns around the world.

## El Niño’s average influence on New Zealand

It’s important to bear in mind that while we know the average outcome of El Niño because of historical data, no El Niño is average—each comes with a unique set of climate characteristics and therefore can be expected to influence the weather differently.

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, which can encourage dryness in eastern areas and more rain in the west. In winter, the winds tend to blow more from the south, causing colder temperatures across the country. In spring and autumn, southwesterly winds are more common.

[![Map of El Nino pressure pattern](/sites/default/files/styles/landscape/public/inline-images/el_nino_pressure_pattern.png?itok=t0sQQs8X)](/sites/default/files/inline-images/el_nino_pressure_pattern.png)

NIWA / data: NCEP

[Attribution, Non-Commercial, No Derivative Work](https://creativecommons.org/licenses/by-nc-nd/4.0  "Attribution, Non-Commercial, No Derivative Work")

A composite, or average, of the summer pressure and wind pattern during 4 different El Niño events. Areas of above normal pressure are shaded in red while areas of below normal pressure are shaded in blue. \[NIWA / data: NCEP\]

## **La Niña**

During a La Niña event, ocean water from off the coast of South America to the central tropical Pacific cools to below average temperatures. This cooling occurs because of stronger than normal easterly trade winds, which churns cooler, deeper sea water up to the ocean’s surface. Sea temperatures can warm above average in the far western Pacific when this happens. The unusually cool water in the eastern Pacific influences the Walker Circulation and suppresses cloud, rain, and thunderstorms. This change impacts weather patterns around the world, but in a different way than El Niño does.

[Play video](https://youtu.be/Jb1KTB5jhsU)

What does La Niña mean for New Zealand?

[Watch Video](https://youtu.be/Jb1KTB5jhsU)

## La Niña’s average influence on New Zealand

Northeasterly winds tend to become more common during La Niña events, bringing moist, rainy conditions to northeastern areas of the North Island and reduced rainfall to the lower and western South Island. Warmer than average air and sea temperatures can occur around New Zealand during La Niña.

[![La Nina pressure pattern and wind](/sites/default/files/styles/landscape/public/2024-03/la-nina.png?itok=nI1QEJ0p)](/sites/default/files/2024-03/la-nina.png)

NIWA / data: NCEP

[Attribution, Non-Commercial, No Derivative Work](https://creativecommons.org/licenses/by-nc-nd/4.0  "Attribution, Non-Commercial, No Derivative Work")

A composite, or average, of the summer pressure and wind pattern during 4 different La Niña events. Areas of above normal pressure are shaded in red while areas of below normal pressure are shaded in blue. \[NIWA / data: NCEP\]

## **Monitoring ENSO: Southern Oscillation Index**

Sir Gilbert Walker documented and named the Southern Oscillation in the 1930s. The clearest sign of the Southern Oscillation is the inverse relationship between surface air pressure at two sites: Darwin, Australia, and the South Pacific island of Tahiti.

Over periods of a month or longer, higher pressure than normal at one site is almost always concurrent with lower pressure at the other, and vice versa. The pattern reverses every few years. It represents a "seesaw" or a mass of air oscillating back and forth across the International Date Line in the tropics and sub-tropics.

The Southern Oscillation Index (SOI) quantifies this pressure difference. Over a period of three months or more, values below -1.0 correspond to El Niño conditions while values above 1.0 correspond to La Niña conditions. Values between -0.5 and -1.0 lean toward El Niño, while values between 0.5 and 1.0 lean toward La Niña. Values between -0.5 and 0.5 are considered neutral.

![](https://webstatic.niwa.co.nz/static/data/weather/soi.png)

Using the SOI, NIWA has compiled a table of historical El Niño and La Niña events as well as maps that help illustrate the average rainfall patterns during historical events.

**ENSO events****Years**Summer – El Niño1972-73, 1977-78, 1982-83, 1986-87, 1991-92, 1992-93, 1994-95, 1997-98, 2004-05, 2009-10, 2015-16Summer – La Niña1973-74, 1975-76, 1988-89, 1998-99, 1999-00, 2000-01, 2007-08, 2008-09, 2010-11, 2011-12, 2020-21, 2021-22Autumn – El Niño1983, 1987, 1992, 1993, 1998, 2005, 2016Autumn – La Niña1974, 1975, 1976, 1989, 1999, 2000, 2008, 2011, 2021, 2022Winter – El Niño1972, 1977, 1982, 1987, 1993, 1994, 1997, 2002, 2015Winter – La Niña1973, 1974, 1975, 1978, 1981, 1988, 1989, 1996, 1999, 2010, 2011, 2013, 2021, 2022Spring – El Niño1972, 1977, 1982, 1987, 1991, 1993, 1994, 1997, 2002, 2006, 2014, 2015Spring – La Niña1973, 1974, 1975, 1988, 1998, 2000, 2008, 2010, 2011, 2017, 2020, 2021\*ENSO events have been subject to an SOI filter of _±0.7 over a five month rolling average period. For example, if the five month rolling average ending in February is at least +0.7, the event is classified as a “La Niña summer”._![New Zealand maps of percentage difference of spring rainfall from normal during La Niña and El Niño from the year 1973 to 2022.](/sites/default/files/styles/wide/public/ENSO-Spring-updated.jpg?itok=oB1de8xG)![New Zealand maps of percentage difference of summer rainfall from normal during La Niña and El Niño from year 1973 to 2022.](/sites/default/files/styles/wide/public/ENSO-Summer-updated.jpg?itok=u2kGznW1)![New Zealand maps of % difference of autumn rainfall from normal during La Niña and El Niño from year 1974 to 2022.](/sites/default/files/styles/wide/public/ENSO-Autumn-updated.jpg?itok=IiJ2kgsN)![New Zealand maps of percentage difference of winter rainfall from normal during La Niña and El Niño.](/sites/default/files/styles/wide/public/ENSO-Winter-updated.jpg?itok=xd5Ck1ce)**_Maps above: brown (green) colours indicate below (above) normal seasonal rainfall._**

## Useful links:

- [Bureau of Meteorology ENSO monitoring website](http://www.bom.gov.au/climate/enso/)
- [NCEP ENSO monitoring website](https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml)

## Further reading:

- [Link to source page](/climate-and-weather/el-nino-and-la-nina/impact-el-nino-and-la-nina-new-zealands-climate)





![](/sites/default/files/styles/card/public/ImminentLandfall_Credit_Katja_Reidel.jpg?h=7feeb858&itok=BvAvKfIz)





## The impact of El Niño and La Niña on New Zealand's climate









El Niño accounts for less than 25 percent of the year-to year variance in seasonal rainfall and temperature at most locations in New Zealand, however its effects can be significant.





[Climate and weather](/climate-and-weather)



[Weather forecasting](/climate-and-weather/weather-forecasting)



[River flow forecasting](/freshwater/river-flow-forecasting)

- [Link to source page](/climate-and-weather/el-nino-and-la-nina/el-nino-maps-and-charts)





![](/sites/default/files/styles/card/public/images/teasers/elnino_chartteaser.jpg?h=7feeb858&itok=BUdcsWGC)





## El Niño maps and charts









View a collection of maps showing the impact of past El Niño and La Niña events.

- [Link to source page](/climate-and-weather/seasonal-climate-outlook)





![Gannet colony](/sites/default/files/styles/card/public/2024-01/2023_PHOTO_COMP_NIWA_HIGH-RES_BreamBay_IreneMiddleton_DSC_7210.JPG?h=fa1c963e&itok=97rfOr_Y)





## Seasonal Climate Outlook







Publication series





Air temperature, rainfall, soil moisture and river flow predictions for the coming season.





[Climate and weather](/climate-and-weather)


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