NIÑO 4+0.1°
1W+0.0°2W+0.1°4W-0.1°
STANDARD VS 1991–2020 +1.0° · SEP 02
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If the forecast proves right, this event would rank among the strongest on record. It is not there yet.
History shows what to watch—not what will happen in your town.
These five readings describe one feedback loop. They are connected, but one does not trigger the next on a fixed timetable. Open any step to see what scientists are watching and why it matters.
Normally, easterly winds push warm surface water toward Indonesia. When those winds weaken or reverse, some of that water can move back east.
Scientists watch whether unusual warmth spreads across the central and eastern Pacific. Warmth that persists across weeks matters more than one hot day.
A deeper layer of warm water can help surface warmth last. It is one reason the ocean can carry useful clues about the months ahead.
Tropical storms tend to form over the warmest water. As that water shifts east, the main zone of rising air and heavy rain can shift with it.
Air pressure and winds can reinforce the ocean change. Scientists call this coupling: the ocean affects the atmosphere, and the atmosphere pushes back on the ocean.
CPC diagnostic discussion explicitly supports historic-watch language.
Official CPC RONI strength distribution updated.
Weekly relative Niño 3.4 moved from 1.4°C to 1.6°C.
NIÑO 1+2 is the warmest zone. Niño 3.4 is the main broad-event gauge; the four boxes show whether warmth is broad or concentrated and how quickly each area is changing.
Scientists split the equatorial Pacific into four named boxes. Niño 4 is farthest west, Niño 3.4 tracks the broad El Niño signal, and Niño 1+2 sits by Peru and Ecuador. A hotter box does not automatically mean worse impacts there.