El Niño Phenomenon
How Pacific sea-surface warming changes rainfall, monsoon, and seasonal weather risks.
El Niño is a recurring warming of the central and eastern tropical Pacific. It changes atmospheric circulation and can shift weather risks far beyond the Pacific basin.
Signals to track
- Sea-surface temperature anomalies in the Niño 3.4 region.
- Trade wind weakening and convection moving eastward.
- Regional rainfall and temperature departures from seasonal normals.
Planning note
El Niño shapes seasonal probabilities; day-to-day decisions still require local forecasts.
Source: Wikimedia Commons El Niño schematic · Mis à jour 2026-06-14