The warming El Nino weather phenomenon could form later this year, potentially pushing global temperatures to record heights.
There is a 50 to 60 percent chance of El Nino developing during the July-September period and beyond, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).
El Nino and its cooler sister, La Nina, are two phases of a natural climate pattern across the tropical Pacific known as the El Nino-Southern Oscillation (ENSO).
Peruvian and Ecuadoran fishermen coined the term El Nino ("the boy" or "the Christ Child") in the 19th century for the arrival of an unusually warm ocean current off the coast that reduced their catch just before Christmas.
Scientists chose the name La Nina as the opposite of El Nino. Between the two events, there is a "neutral" phase.
El Nino can weaken consistent trade winds that blow east to west across the tropical Pacific, influencing weather by affecting the movement of warm water across this vast ocean.
This weakening warms the usually cooler central and eastern sides of the ocean, altering rainfall over the equatorial Pacific and wind patterns around the world.
The extra heat at the surface of the Pacific releases energy into the atmosphere that can temporarily drive up global temperatures, which is why El Nino years are often among the warmest on record.
"All else being equal, a typical El Nino event tends to cause a temporary increase in the global mean temperature on the order of 0.1 to 0.2 degrees Celsius," Nat Johnson, an NOAA meteorologist, told AFP.
El Nino occurs every two to seven years.
It typically results in drier conditions across southeast Asia, Australia, southern Africa, and northern Brazil, and wetter conditions in the Horn of Africa, the southern United States, Peru and Ecuador.
The last El Nino occurred in 2023-2024, contributing to making 2023 the second highest year on record and 2024 the all-time high.
Carlo Buontempo, director of the European Union's Copernicus Climate Change Service, told AFP in January that 2026 could be "another record-breaking year" if El Nino appears this year.
However, El Nino's impact would be higher in 2027 than in 2026 if it develops in the second half of this year, said Tido Semmler, a climate scientist at Ireland's National Meteorological Service.
The latest La Nina episode was relatively weak and short lived, starting in December 2024 and due to enter a neutral phase during the February-April period.
La Nina cools the eastern Pacific Ocean for a period of about one to three years, generating the opposite effects to El Nino on global weather.
La Nina did not stop 2025 from being the third hottest on record.
