The World Meteorological Organization (WMO) has issued its most confident forecast on record, saying there is a "nearly 100% likelihood" that the current strong El Niño will persist through February 2027. The UN weather agency says this event is on track to be the strongest El Niño ever recorded, with UN Secretary-General António Guterres warning it is being "supersized before our eyes" and that the planet is entering a "danger zone" of extreme weather. Because El Niño typically raises global average temperatures on top of existing human-caused warming, scientists expect this year to be the hottest on record, with 2027 potentially even hotter as the extra heat works through the climate system.

El Niño occurs when ocean surface temperatures in the eastern tropical Pacific rise above normal, disrupting weather patterns worldwide; it usually adds around 0.1–0.2°C to global average temperatures. Effects are already visible, including the hottest US summer on record, drought worsening a hunger crisis linked to low Nile water levels in Sudan, water rationing in Puerto Rico, and disruption to fisheries in the eastern Pacific. Climate scientist Daniel Swain described it as potentially one of the largest climate events anyone alive has experienced, cautioning that its scale makes specific impacts hard to predict, while a separate UN report warned the world is likely to breach 1.5°C of warming within the next few years.