El Niño and La Niña are opposite phases of the El Niño–Southern Oscillation, or ENSO, one of the most influential natural climate patterns on Earth. El Niño is marked by unusually warm ocean surface temperatures in the central and eastern equatorial Pacific. It typically develops every two to seven years, lasts about nine to 12 months, and often begins forming between March and June before peaking between November and February. Its climate effects are often strongest in the second year after it develops.
The impact of each event depends on its strength, duration, timing, and interaction with other climate patterns such as the Indian Ocean Dipole. That means no two El Niño or La Niña events are exactly alike. Some regions may experience major effects while others see little change. Even when ENSO is neutral, severe weather can still occur. WMO notes that ENSO intensity matters greatly, with even moderate El Niño events increasing the likelihood of weather and climate extremes. The organization does not use the term “super El Niño” because it is not part of standardized operational classifications.
Climate change does not appear to increase the frequency or intensity of El Niño events, according to WMO. However, it can worsen the effects, since warmer oceans and atmospheres provide more energy and moisture for extreme events such as heatwaves and heavy rainfall.
Typical El Niño patterns include wetter conditions in parts of southern South America, the southern United States, the Horn of Africa, and central Asia. At the same time, drier weather is often seen in Central America, northern South America, the Caribbean, Australia, Indonesia, and parts of southern Asia. During boreal summer, El Niño can also influence tropical cyclones, helping fuel hurricane activity in the central and eastern Pacific while suppressing hurricane formation in the Atlantic Basin.
That Atlantic suppression is one reason NOAA is forecasting a below-normal Atlantic hurricane season this year. At the same time, climate outlook forums and meteorological agencies are issuing region-specific warnings. In the Greater Horn of Africa, below-normal rainfall is expected across much of the northern area during the crucial June to September rainy season. South Asia is also forecast to receive below-average monsoon rainfall, while Central America is expected to face hotter and drier conditions.
WMO’s Global Seasonal Climate Update also factors in other major climate drivers, including the North Atlantic Oscillation, the Southern Annular Mode, and the Indian Ocean Dipole. For June through August, forecasts show above-normal temperatures across nearly the entire globe. This raises the risk of heat stress, worsens drought in places with reduced rainfall, and increases the chance of compounding hazards such as flooding, drought, and extreme heat.
