What is El Niño?
El Niño is a lasting warming of the ocean surface in the central and eastern tropical Pacific. The usual east-to-west winds weaken and tropical rain patterns shift, changing weather around the world.
La Niña is the cooler phase of the same cycle, with stronger winds. Neutral means neither phase is established. Together, these phases are called ENSO.
Where are the Niño regions?
Scientists average sea surface temperatures (SSTs) across these four ocean areas. Niño 3.4, highlighted below, is the main region used to measure El Niño and La Niña.
What does “above average” mean?
Compare a region with its usual temperature for that time of year. Zero means usual. +1°C means one degree warmer; −1°C means one degree cooler. The numbers below are temperature differences.
La Niña
−1.0°C−1.8°FNeutral
0.0°C0.0°FEl Niño
+1.0°C+1.8°FFor NOAA’s three-month index, El Niño starts at +0.5°C and La Niña at −0.5°C. Winds and rainfall must also fit the pattern, which persists for months.
What do “strong” and “super” mean?
Forecasters use a three-month temperature measure for Niño 3.4. The farther it moves from zero, the stronger the ocean signal.
For La Niña, the same strength steps run below zero.
“Super El Niño” is an informal nickname for a very strong event, often around +2°C (+3.6°F) or more. It has no separate official definition. Local rain and heat still depend on other weather patterns.
Reading this dashboard
NOAA’s official measure, RONI, also adjusts for how warm the tropics are overall. The guides illustrate that index; our dashboard shows weekly temperatures against its own historical average. Visit NOAA’s El Niño guide for the official background.