Archive · 4 Oct 2026
Why El Niño Brings Drought to Some Regions
El Niño happens when the winds over the tropical Pacific become weaker than usual.
Warm ocean water then spreads farther east.
Air above the warm water rises and forms clouds and rain, so some places near the eastern Pacific can get wetter.
Meanwhile, air sinks over parts of the western Pacific, making clouds and rain less likely.
That can leave places such as Indonesia much drier.
Changes in the atmosphere can also affect weather far from the Pacific.
These effects can influence places such as the Sahel and Britain.
El Niño changes what kinds of weather are more likely, but it does not decide every storm or rainy day.
El Niño weakens the Pacific trade winds, allowing more warm water to remain in the central and eastern Pacific.
The main zone of rising moist air and rainfall shifts east, bringing wetter conditions to parts of the eastern Pacific, including coastal Peru.
Sinking air over Indonesia and nearby areas makes clouds and rain less likely, increasing drought and fire risks.
Atmospheric heating shifts can affect rainfall and storm patterns far beyond the Pacific, including in the Sahel and Britain.
El Niño changes the odds of certain weather patterns, but local weather systems can still cause heavy rain and flooding.
- Who
- El Niño affects weather in regions around the world.
- What
- A shift of warm Pacific water and atmospheric circulation changes rainfall patterns, increasing drought risk in some places and rain risk in others.
- When
- The article describes this year's El Niño, which forecasters expect to strengthen before its usual peak around December.
- Where
- The tropical Pacific and regions including Indonesia, coastal Peru, the Sahel, Britain, Thailand, and India.
- Why
- Weakened trade winds shift warm water and rising moist air eastward, changing atmospheric circulation and rainfall patterns.
- Climate pattern
- El Niño is the warm phase of a natural fluctuation in Earth's climate system.
- Typical trade winds
- They usually blow from east to west across the tropical Pacific, pushing warm surface water westward.
- Ocean process
- Upwelling brings colder water to the surface in the eastern Pacific.
- Rainfall shift
- During El Niño, the main zone of rising moist air and rainfall moves toward the central and eastern Pacific.
- Western Pacific effect
- Sinking air can reduce cloud formation and rainfall around Indonesia, increasing drought and fire risks.
- Long-distance effects
- Atmospheric heating and ripples can influence weather far beyond the Pacific.
- Forecast timing
- Forecasters expect this year's El Niño to strengthen before approaching its usual peak around December.