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El Niño vs. La Niña

Summary

El Niño and La Niña are opposite phases of the El Niño-Southern Oscillation (ENSO) in the tropical Pacific. During El Niño, the trade winds weaken and warm water moves east toward the Americas. During La Niña, the trade winds strengthen and cold upwelling increases off the Americas. Each phase shifts the jet stream and changes weather around the world.

Draft. License: CC BY 4.0 (this summary). Sources: [S1] NOAA National Ocean Service, "What are El Niño and La Niña?" (public domain (US government work)).

Facts

• id: F1 claim: Normally, trade winds blow west along the equator, moving warm water toward Asia, and cold water rises (upwelling) off South America. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F2 claim: El Niño and La Niña are two opposing patterns that break these normal conditions; together they are called the El Niño-Southern Oscillation (ENSO) cycle. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F3 claim: Episodes typically last 9-12 months but can last years, and occur every two to seven years on average, irregularly; El Niño generally occurs more often than La Niña. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F4 claim: During El Niño, trade winds weaken and warm water moves east toward the west coast of the Americas. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F5 claim: El Niño pushes the Pacific jet stream south; in winter the northern US and Canada tend to be warmer and drier, and the US Gulf Coast and Southeast wetter, with more flooding. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F6 claim: During El Niño, upwelling off the Pacific coast weakens or stops, so fewer nutrients reach the surface and phytoplankton decline, affecting fish and the animals that eat them. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F7 claim: During La Niña, trade winds are stronger than usual and upwelling off the Americas increases, bringing cold, nutrient-rich water. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F8 claim: La Niña pushes the jet stream north, tending toward drought in the southern US and heavy rain in the Pacific Northwest and Canada, and can lead to a more severe hurricane season. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02
• id: F9 claim: 'El Niño' means 'little boy' in Spanish and 'La Niña' 'little girl'; El Niño typically peaks around December. confidence: medium date: 2026-11-02 sources: [S1] license: CC BY 4.0 checked_on: 2026-11-02

Caveats

• These are typical tendencies, not guarantees for any single season.
• For current ENSO status, check NOAA's Climate Prediction Center.

Pointers

• id: P1 answers: Current ENSO status and outlook where: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ access: free, public web page

@misc{iil_note_nnycagam,
  author = {{iinventedlight Library}},
  title = {{El Niño vs. La Niña}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-02},
  url = {https://iinventedlight.com/library/reference/us-gov/el-nino-la-nina/},
  note = {Permanent ID iil:note:nnycagam. License: CC-BY-4.0. Summary of https://oceanservice.noaa.gov/facts/ninonina.html.},
}

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