The Pacific Ocean is warming unusually fast this year, and the current El Niño has already exceeded previous records, with forecasters expecting further strengthening toward its December peak.

Normally, east‑to‑west trade winds push warm surface water toward Indonesia, where it piles up, while colder deep water rises in the east, creating a strong temperature contrast that fuels rainfall over the western Pacific and leaves the eastern Pacific relatively dry.

During an El Niño event the trade winds weaken, allowing warm water to remain in the central and eastern Pacific; this shift moves the region of strongest evaporation, rising moist air, and cloud formation eastward, bringing wetter conditions to places such as coastal Peru.

Conversely, the western Pacific receives less warm water and experiences reduced upward motion, so sinking air suppresses cloud formation, making Indonesia and nearby regions drier and raising the risk of forest and peatland fires.

The weakened temperature contrast also diminishes the pressure gradient that drives the trade winds, further weakening the Walker circulation and reinforcing the eastward shift of atmospheric heating.

These Pacific changes generate “teleconnections” that affect distant regions; for example, the altered heating can warm the upper tropical atmosphere over the Sahel, suppressing rising moist air and leading to drier conditions there.

Another pathway involves atmospheric ripples that travel far from the Pacific, modifying wind patterns and storm tracks, which can increase the likelihood of wetter, stormier autumns in Britain and affect other mid‑latitude regions.

El Niño can also interact with the Indian Ocean dipole, a temperature seesaw that influences rainfall over East Africa and India, adding another layer of complexity to regional climate outcomes.