🌊 El Niño & La Niña

ENSO status, forecast, and the story behind the Pacific's biggest swing · CPC + IRI · updated 2026-10-02 4:37 PM ET

📡 Current status

EL NINO El Niño Advisory

ENSO Alert System Status: El Niño Advisory Synopsis: El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27. El Niño strengthened further over the past month, with sea surface temperature anomalies exceeding +3.0°C in the eastern equatorial Pacific [Fig. 1] . Except for the Niño-4 index, which decreased to +0.1°C in August, values in the other Niño indices increased, reaching +1.8°C in Niño-3.4, +2.5°C in Niño-3, and +3.4°C in Niño-1+2 [Fig. 2] . The equatorial subsurface temperature index (average from 180°-100°W) remained steady during August [Fig. 3] , reflecting a deeper-than-average thermocline [Fig. 4] . Subsurface temperatures continued to be significantly above average, with widespread anomalies in excess of +10.0°C at depth. Low-level westerly wind anomalies and upper-level easterly wind anomalies extended from the western to the east-central equatorial Pacific. Enhanced convection and rainfall persisted from the central to the eastern Pacific, while anomalies remained suppressed over Indonesia [Fig. 5] . The traditional and equatorial Southern Oscillation indices remained negative. Collectively, the coupled ocean-atmosphere system reflected a strengthening El Niño. The CPC Official ENSO outlook , which synthesizes multiple models from North America and abroad, indicates El Niño will continue to strengthen through the end of the year [Figs. 6

-8] . During the October-December 2026 season, there is a 75% chance of a historic event that would exceed the strength of previous El Niño events dating back to 1950 (+2.5°C or more for a 3-month RONI value ). With an event of this magnitude, the chances of experiencing impacts consistent with El Niño are larger, though not guaranteed (see CPC outlooks for probabilities of seasonal anomalies). In summary, El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27. This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (

90%

…ENSO Alert System Status: El Niño Advisory Synopsis: El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27.

75%

…During the October-December 2026 season, there is a 75% chance of a historic event that would exceed the strength of previous El Niño events dating back to 1950 (+2.5°C or more for a 3-month RONI value ).

90%

In summary, El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27.

Percentages are CPC's official odds from the monthly ENSO Diagnostic Discussion - the same statement forecasters use. Strength scale: weak (+0.5 to +1.0) · moderate (+1.0 to +1.5) · strong (+1.5 to +2.0) · very strong (+2.0 and beyond).

🌡️ Nino 3.4 sea-surface temperature anomaly - last 24 months

The dashed lines are the official thresholds: sustained anomalies beyond ±0.5°C define an ENSO event; ±1.0°C moderate, ±1.5°C strong, ±2.0°C very strong. Hover for exact values.

📈 Every El Niño & La Niña since 1950

Oceanic Nino Index - 3-month running mean Nino 3.4 anomaly. Red = El Niño seasons, blue = La Niña. The biggest events (1982-83, 1997-98, 2015-16) reshaped global weather; the labeled marks call out the strongest on record.

🎯 Seasons like this one - analog years

Current: JJA 2026 ONI +1.80°C (strong)

Winter	DJF ONI	Diff from now
2023-24	+1.84°C	+0.04
1957-58	+1.69°C	-0.11
1972-73	+1.55°C	-0.25
1991-92	+1.54°C	-0.26
2009-10	+1.47°C	-0.33
1982-83	+2.14°C	+0.34
1997-98	+2.22°C	+0.42
1965-66	+1.24°C	-0.56

The historical winters whose ENSO state sat closest to today's - the analogs a forecaster checks first. Find their winters in the table below to see what NAO/PNA did on top of the ENSO signal.

🏆 The record book - strongest since 1950

Winter	Peak ONI	Strength	Run	Winter teleconnections
2015-16	+2.59°C	very strong	SON 2014–AMJ 2016 (20 seasons)	NAO+ PNA+
1997-98	+2.37°C	very strong	AMJ 1997–MAM 1998 (12 seasons)	NAO~ PNA+
1982-83	+2.14°C	very strong	AMJ 1982–MJJ 1983 (14 seasons)	NAO+ PNA+
1973-74	-2.04°C	very strong	AMJ 1973–MJJ 1974 (14 seasons)	NAO+ PNA~
1988-89	-1.85°C	strong	AMJ 1988–AMJ 1989 (13 seasons)	NAO+ PNA~
2007-08	-1.76°C	strong	JAS 2007–MJJ 2008 (11 seasons)	NAO+ PNA~

Official CPC episode detection: 5+ consecutive 3-month seasons beyond ±0.5°C in Nino 3.4; strength graded at the peak (moderate ±1.0, strong ±1.5, very strong ±2.0). NAO/PNA are Dec–Feb means of CPC's standardized monthly indices - the extra cards that split otherwise-similar ENSO winters into very different outcomes.

⏳ The marathons - longest runs

Winter	Peak ONI	Strength	Run	Winter teleconnections
2015-16	+2.59°C	very strong	SON 2014–AMJ 2016 (20 seasons)	NAO+ PNA+
1986-87	+1.49°C	moderate	ASO 1986–DJF 1988 (17 seasons)	NAO~ PNA+
1998-99	-1.53°C	strong	JJA 1998–MJJ 2000 (24 seasons)	NAO+ PNA~
1970-71	-1.36°C	moderate	JJA 1970–DJF 1972 (19 seasons)	NAO- PNA-

🧭 Last 15 winters: ENSO × NAO × PNA

Winter	DJF ONI	NAO		PNA
2025-26	-0.39°C	-0.11	NAO~	-0.39	PNA~
2024-25	-0.46°C	+0.76	NAO+	+1.39	PNA+
2023-24	+1.84°C	+1.08	NAO+	+0.58	PNA+
2022-23	-0.55°C	+0.68	NAO+	-0.36	PNA~
2021-22	-0.76°C	+1.02	NAO+	-0.30	PNA~
2020-21	-0.99°C	-0.42	NAO~	+0.49	PNA~
2019-20	+0.71°C	+1.27	NAO+	+0.04	PNA~
2018-19	+0.99°C	+0.50	NAO+	+0.21	PNA~
2017-18	-0.71°C	+1.30	NAO+	+0.09	PNA~
2016-17	-0.08°C	+0.65	NAO+	+0.04	PNA~
2015-16	+2.50°C	+1.31	NAO+	+1.43	PNA+
2014-15	+0.73°C	+1.66	NAO+	+0.62	PNA+
2013-14	-0.24°C	+0.86	NAO+	-0.28	PNA~
2012-13	-0.24°C	+0.02	NAO~	-0.01	PNA~
2011-12	-0.71°C	+1.37	NAO+	+0.57	PNA+

Tags: + beyond +0.5, − beyond −0.5, ~ neutral in between (CPC standardized monthly indices, Dec–Feb mean). Same ENSO, different NAO: 2015-16 (very strong El Niño + NAO+) and 2009-10 (moderate El Niño + NAO−) delivered very different eastern-US winters.

🏔️ Landmark winters - when history was made

1992-93 · The Storm of the Century (Mar 12-13, 1993)

ENSO neutral (+0.13°C) NAO +0.86 NAO+ PNA -0.44 PNA~

A hurricane-scale blizzard covering ~1.3 million square miles from the Gulf Coast to Canada - thundersnow in Tennessee, record lows in its wake. Officially a NEUTRAL winter (DJF ONI +0.13): the tail of the strong 1991-92 El Nino plus a strongly positive NAO (Mar 1993 +0.67). ENSO set the stage; the NAO threw the punch.

1995-96 · Blizzard of '96 (Jan 1996)

ENSO weak (-0.88°C) NAO -0.62 NAO- PNA +0.20 PNA~

The East Coast classic - up to 30in on NYC/DC - in a moderate La Nina winter (DJF -0.88) with negative-NAO blocking; the La Nina + blocking combo that can bury the East even without El Nino.

2009-10 · Snowmageddon (Feb 2010)

ENSO moderate (+1.47°C) NAO -1.67 NAO- PNA +0.72 PNA+

Washington DC's back-to-back 20in+ storms during a strong El Nino (+1.47) with one of the strongest negative NAOs on record (-1.67) - the textbook case of the NAO card beating the ENSO card for who gets the snow.

Curated companions to the tables above: famous winters whose full ENSO/NAO/PNA context the episode rule alone cannot show. The Storm of the Century struck in an officially NEUTRAL winter - proof the teleconnection tags, not just the ENSO phase, decide who gets the history-making storm.

🔮 The forecast

IRI/CPC dynamic-model plume - what ~20 models think Nino 3.4 does next:

IRI dynamic-model Nino 3.4 forecast plume

Each line: one dynamical or statistical model's forecast of Nino 3.4 SST anomaly through the coming seasons - the spaghetti of forecasts the official CPC probability statement is built from.

Official CPC advisory graphics (current figures rotate with each monthly discussion):

Sea-surface temperature anomalies (12-month loop)

Advisory figure 1 - NOAA CPC ENSO Diagnostic Discussion

Advisory figure 2 - NOAA CPC ENSO Diagnostic Discussion

Advisory figure 3 - NOAA CPC ENSO Diagnostic Discussion

Advisory figure 4 - NOAA CPC ENSO Diagnostic Discussion

Read the plume like a spread chart: where the lines fan apart, the models disagree about how strong the event gets; where they bunch, the forecast is confident. The CPC statement above blends these models with forecaster judgment.

🧭 What El Niño actually is

Along the equator, the Pacific has two natural states. In the neutral state, steady trade winds blow east-to-west, piling warm water into the western Pacific (the "warm pool") while cold, nutrient-rich water upwells off South America. Thunderstorms fire over the warm pool, driving a huge east-west circulation called the Walker circulation.

El Niño is when the trade winds weaken or reverse: the warm pool sloshes back east, the central and eastern equatorial Pacific warms several degrees above normal, and the storm factory moves with it. The atmosphere and ocean reinforce each other in a feedback loop (Bjerknes feedback) that can push the event to historic strength. La Niña is the mirror image - stronger trades, colder eastern Pacific.

Forecasters measure it in the Niño 3.4 region (5°N-5°S, 170°W-120°W). The Oceanic Nino Index (ONI) is that region's 3-month running SST anomaly versus the 1991-2020 average; five consecutive seasons beyond +0.5°C is an El Niño event, beyond -0.5°C a La Niña. Events come every 2-7 years and usually peak around December ("Niño" - the Christ child - named by Peruvian fishermen for that timing).

🏘️ What it means for Tennessee

El Niño winters: the Pacific jet stream strengthens and sags south, steering wet storms across the southern U.S. The typical Tennessee read is a cooler, wetter winter - more Gulf-fed rain systems, better snow/ice odds when cold air taps in.

El Niño hurricane seasons: stronger upper-level winds shear Atlantic storms apart. The Atlantic typically sees fewer, weaker hurricanes - while the East Pacific gets busier (its systems' moisture can still flood the Southwest).

La Niña winters flip the pattern: the northern jet dominates, giving Tennessee drier, warmer winters - and the following spring often brings an earlier, more active severe weather season in the Tennessee Valley, plus busier Atlantic hurricane seasons.

These are typical tendencies, not guarantees - El Niño loads the dice, it doesn't pick the roll. Pair this page with the Climate page's official CPC seasonal outlooks.

Sources: NOAA CPC ENSO Diagnostic Discussion (monthly or as advisories change), CPC ONI & monthly SST indices, IRI ENSO forecast plume. Graphics mirrored locally for speed; text refreshed on the site update cycle. El Niño threshold +0.5°C · La Niña threshold -0.5°C (CPC ONI, 1991-2020 base period).