The World Meteorological Organization (WMO) is set to release an updated assessment of El Niño conditions on Tuesday, as concerns grow that the climate pattern could develop later this year and exacerbate already rising global temperatures.
The U.S. National Oceanic and Atmospheric Administration (NOAA) currently estimates a 50- to 60-percent chance of El Niño forming during the July-September period and continuing thereafter. This potential development comes after a relatively weak and short-lived La Niña event, which entered a neutral phase during February-April of this year.
El Niño and La Niña are opposing phases of the El Niño-Southern Oscillation (ENSO), a natural climate pattern in the tropical Pacific Ocean. The term “El Niño,” meaning “the boy” or “the Christ Child” in Spanish, was originally coined by Peruvian and Ecuadorian fishermen in the 19th century to describe the arrival of unusually warm ocean currents around Christmas time, which often diminished their catches. Scientists later adopted “La Niña” as the name for the opposite phenomenon.
El Niño’s warming effect is triggered by a weakening of the typical east-to-west trade winds across the Pacific. This allows warm water to accumulate in the central and eastern Pacific Ocean, altering rainfall patterns and global wind circulation. The resulting release of heat into the atmosphere can contribute to temporarily higher global temperatures, making El Niño years frequently among the warmest on record.
The last El Niño event occurred from 2023 to 2024 and played a role in making 2023 the second warmest year ever recorded, and 2024 the warmest. Carlo Buontempo, director of the European Union’s Copernicus Climate Change Service, indicated in January that 2026 could potentially surpass previous temperature records if El Niño emerges this year. Still, climate scientists like Tido Semmler of Ireland’s National Meteorological Service, caution that the full impact of a developing El Niño may be more pronounced in 2027, as it takes time for the global atmosphere to respond. Semmler as well noted that even without El Niño, 2026 carries a risk of becoming a record-breaking year due to the ongoing trend of global warming.
The typical impacts of El Niño include drier conditions in Southeast Asia, Australia, southern Africa, and northern Brazil, although the Horn of Africa, the southern United States, Peru, and Ecuador often experience increased rainfall. La Niña, conversely, tends to bring wetter conditions to parts of Australia, Southeast Asia, India, southeast Africa, and northern Brazil, and drier conditions to parts of South America.
NOAA recently adopted a new method for determining El Niño and La Niña events, shifting from the Oceanic Niño Index (ONI) to the Relative Oceanic Nino Index (RONI). The previous ONI method compared sea surface temperatures in a specific Pacific region to a 30-year average in the same area. However, with rapidly warming oceans, this 30-year baseline became increasingly outdated. The new RONI method assesses how warm or cool the east-central Pacific is relative to the rest of the tropics, which NOAA describes as a “clearer, more reliable way” to track these climate patterns in real time.
