El Niño and La Niña Years: The Complete List Since 1950, Ranked by Strength

The Strongest El Niños and La Niñas, Ranked

Ranked by peak Oceanic Niño Index — the single strongest three-month ocean temperature anomaly reached during each event. Values are NOAA CPC ONI in degrees Celsius.

The asymmetry is real and worth noticing: the top El Niños blow past the top La Niñas. Three El Niños have topped +2.0°C; only one La Niña has ever reached −2.0°C. The warm phase simply has more headroom. That is also why a “super El Niño” is a once-a-decade-ish event — before 2026, the last three were 1982-83, 1997-98 and 2015-16, each separated by about 15 to 18 years.

Every El Niño and La Niña Winter Since 1950

The full chronology. Each row is the winter (Dec–Feb), its ENSO phase, the peak Oceanic Niño Index it reached, and NOAA's strength class. Winters not listed were ENSO-neutral — the ocean stayed within ±0.5°C of normal and neither phase took hold. There are 26 El Niño winters and 25 La Niña winters in all.

*2026-27 is still developing: +2.16°C is the ONI through July–September 2026 (the latest value in the NOAA file), not a final peak. NOAA's October 8 outlook gives it an 83% chance of becoming the strongest event since 1950. We'll lock in its final class after the winter peak — follow it on the El Niño 2026 tracker.

What the Numbers Mean: ONI and the Four Classes

Every label in the tables above comes from one measurement. The Oceanic Niño Index is the three-month running average of the sea-surface temperature anomaly in the Niño-3.4 region of the equatorial Pacific. When that running average holds at or above +0.5°C for five consecutive overlapping three-month seasons, NOAA calls it an El Niño; at or below −0.5°C, a La Niña. In between is neutral.

The strength classes follow the peak the ONI reaches:

One honest caveat on the edges. We class each winter by its single strongest ONI value, which is the most transparent way to rank them — the number next to each year is exactly what it met. NOAA and the widely cited ggweather ONI table add a second rule — the threshold has to hold for three consecutive seasons — so a few borderline winters (1987-88 at +1.41, 1991-92 at +1.54, 2009-10 at +1.50, 2023-24 at +1.99) land one class higher or lower in those references. We print the peak ONI so you can see the margin and judge for yourself.

El Niño vs La Niña, in One Minute

El Niño and La Niña are the two phases of the same engine — the El Niño–Southern Oscillation, or ENSO — and they are defined entirely by the temperature of one stretch of the tropical Pacific. El Niño is the warm phase: the central and eastern equatorial Pacific runs warmer than normal, the ONI sits at +0.5°C or higher, and the extra ocean heat shoves the winter jet stream so that the southern US tends wetter and stormier while the Pacific Northwest and Ohio Valley tend milder and drier. La Niña is the cool phase — ONI at −0.5°C or lower — and it roughly flips the map: a drier, warmer South and a wetter, colder northern tier. Neither is a forecast on its own; each one loads the dice for a season, and the strength (those ONI numbers) is how hard the dice are loaded.

Where the 2026-27 El Niño Could Land — and What a Strong One Does

A strong-to-very-strong El Niño is already in place for winter 2026-27. The ONI reached +2.16°C in July–September 2026 and is forecast to keep climbing toward a December peak. In its October 8 diagnostic, NOAA's Climate Prediction Center gave an 83% chance the event becomes “historic” — a relative ONI above +2.5°C that would top every El Niño since 1950, surpassing the +2.6°C record set in 2015-16, with ECMWF projecting central-Pacific anomalies near +3°C by December. If it holds, 2026-27 becomes the fourth very-strong El Niño on record and quite possibly the strongest.

What that tends to mean for the US, based on the strong events in the table: a milder, drier northern tier and an active southern storm track. We break down the specifics rather than rebuild them here — the city-by-city snow lean is in does El Niño mean more snow, the temperature-and-precipitation outlook for 21 cities is in the Super El Niño winter forecast, and the state-level pattern is in El Niño effects by state. El Niño also quiets the Atlantic — the record of that is in El Niño hurricane seasons.

Frequently Asked Questions

Sources & Method — Check It Yourself

Every number on this page comes from NOAA's Climate Prediction Center Oceanic Niño Index, pulled from the agency's machine-readable file oni.ascii.txt (seasonal ONI, DJF 1950 through July–September 2026). We flag a winter as El Niño or La Niña when the ONI met NOAA's ±0.5°C threshold for at least five consecutive overlapping three-month seasons, label each by the winter it spans, take its single strongest ONI value in the September–April window as the peak, and class it on NOAA's thresholds (Weak 0.5–0.9, Moderate 1.0–1.4, Strong 1.5–1.9, Very Strong ≥ 2.0). The published ggweather ONI classification uses the same NOAA data with an added three-consecutive-season rule; the two agree on every event and on all three very-strong El Niños, and differ only by one class on a handful of borderline winters, which we flag above. The 2026-27 forecast strength is from NOAA CPC's ENSO Diagnostic Discussion. If you want the raw monthly numbers for a specific year, the NOAA file above is the primary source; for how past ENSO winters actually played out at your city, start from the US weather records hub.