The 2023-2024 El Niño was one of the five strongest on record. Combined with long-term global warming, it produced the hottest year in recorded history, triggered devastating floods in East Africa and Peru, drove extreme drought in the Amazon, and contributed to a record-breaking Atlantic hurricane season as it faded. This review examines what happened, how strong it actually was, and what we learned.
Timeline and Intensity
NOAA declared El Niño conditions in June 2023. Sea surface temperatures in the Niño-3.4 region rose steadily, reaching the El Niño threshold of 0.5°C above average by April-May. The event peaked in November-December 2023 with Niño-3.4 anomalies around 2.0°C — qualifying as a "strong" El Niño, though short of the 2.3-2.6°C peaks of 1997-98 and 2015-16.
The event then declined through spring 2024, with neutral conditions returning by May 2024. Total duration: approximately 11 months, a fairly typical El Niño lifespan. By June 2024, forecast models were already pointing toward a potential La Niña transition by late 2024.
Global Temperature Records
2023 was the hottest year in the instrumental record, with a global average temperature approximately 1.45°C above pre-industrial levels. Every month from June 2023 through May 2024 set a new monthly temperature record. The combination of strong El Niño and background warming pushed the planet into territory never before observed. July 2023 was the hottest month ever recorded, with July 6 becoming the hottest single day ever (global average 17.23°C).
What made this event notable: even before El Niño fully developed, global temperatures were already breaking records. April, May, and June 2023 — before El Niño was officially declared — each set new monthly records, suggesting the background warming trend is accelerating independent of ENSO variability.
Regional Impacts
East Africa: Catastrophic floods in Kenya, Somalia, and Ethiopia killed over 500 people and displaced 1.5 million during October-November 2023, the "short rains" season amplified by El Niño.
Peru and Ecuador: Heavy rains and flooding hit coastal regions in early 2024. Dengue outbreaks surged as floodwaters created mosquito breeding grounds — Peru declared a health emergency.
Amazon Rainforest: Severe drought gripped the northern Amazon. The Rio Negro in Manaus, Brazil fell to its lowest level in 121 years of record-keeping. River dolphins died from heat stress as water temperatures exceeded 39°C.
Southeast Asia: Delayed monsoon onset and below-average rainfall in Indonesia and the Philippines reduced rice yields and drove up global rice prices.
Southern United States: A wet winter across the Gulf Coast and California brought drought relief but also localized flooding. Los Angeles received nearly double its annual average rainfall.
How It Compared to Previous Events
The 2023-24 El Niño was somewhat weaker in ocean temperatures than 1997-98 and 2015-16, but it produced larger global temperature anomalies because the underlying planet is warmer. The event itself was unremarkable by "Super El Niño" standards, but its effects were amplified by an atmosphere already primed by 1.2°C of global warming.
Lessons for the 2026-27 Event
The 2023-24 El Niño provided several critical lessons that directly inform expectations for the 2026-27 event. First, the global temperature response to even a moderate-strong El Niño is now amplified by the warmer baseline — each successive event breaks records, even if the ocean anomaly itself is smaller. Second, the rapid transition between ENSO phases (La Niña 2020-23 directly into El Niño 2023-24) demonstrated that the climate system can flip faster than previously assumed, reducing the window for preparation. Third, the 2023-24 event showed that drought conditions in key regions like the Amazon can develop much faster and more severely than models predicted, suggesting that risk assessments for 2026-27 should use conservative (worse-case) assumptions for drought and fire risk in vulnerable ecosystems. Fourth, the dengue and malaria outbreaks that followed the 2023-24 floods in Peru and East Africa highlight the need for early public health interventions — vector control measures deployed before the rainy season can significantly reduce disease burden.
Regional Economic Impact Comparison
The economic toll of El Niño isn't evenly distributed. Some regions absorb glancing blows while others take direct hits. The map below shows how 2023-2024 review varies across the most vulnerable regions — and why preparedness investments produce vastly different returns depending on where you are.
| Region | Estimated GDP Impact | Primary Channel | Recovery Time |
|---|---|---|---|
| Southeast Asia | -0.5% to -2.0% | Agriculture + drought | 1–2 years |
| Andean South America | -1.0% to -3.0% | Fisheries + flooding + infrastructure | 2–4 years |
| East Africa | -0.5% to -1.5% | Agriculture + food imports | 1–2 years |
| Southern Africa | -1.0% to -2.5% | Drought + hydropower | 2–3 years |
| Australia | -0.3% to -1.0% | Agriculture + bushfire costs | 1 year |
| India | -0.2% to -1.0% | Monsoon agriculture | 1–2 years |
| Central America | -1.0% to -2.0% | Drought + coffee/banana exports | 2–3 years |
The most vulnerable countries are those where agriculture accounts for a large share of GDP AND the climate is strongly teleconnected to ENSO. A country like Peru, where the fishing industry alone represents ~2% of GDP and is directly disrupted by El Niño warming, feels the impact faster and harder than a diversified economy with weaker ENSO links.
For the 2026-2027 event, the economic exposure is compounded by already-strained fiscal positions in many developing countries following the pandemic recovery period. Limited fiscal space means less capacity to absorb shocks through government spending — making early warning and preparedness even more critical.