CPCLoading NOAA's status…
Interstate 10 · Santa Monica to Jacksonville
El Niño is a trajectory, not a single event.
The tropical Pacific now, the path it took to get here, and what that whole path has meant for U.S. winters, with the sample size on every number.
Every index, side by side
Latest valuesDifferent indices answer different questions, which is why the press quotes different numbers for the same event. The weekly readings are the freshest. The three-month and relative indices are NOAA's official yardsticks. MEI-ERA5 carries the record back to 1940.
Day by day, to yesterday
OSTIA dailyThe four Niño boxes, last six months
Daily sea-surface temperature anomalies. The eastern boxes (Niño-1+2 off Peru, Niño-3) lead. The central box (Niño-4) barely moves, the signature of an eastern-Pacific event.
Record watch
This event against every event on recordIs it a record yet? It depends on the index.
Each row compares this event's peak so far (since January 2026) with the highest value before 2026, on the same index, from the same source. Forecast rows are forecasts, not observations.
| Index | Latest | Peak this event | Record before 2026 | Status |
|---|
What the models say
Copernicus multi-systemNiño-3.4, observed and forecast
Which kind of El Niño
Eastern vs central PacificThe warmth is in the east
How much warmer Niño-3 (the eastern box) runs than Niño-4 (the central box). Large values mark the classic eastern-Pacific events whose U.S. impacts are the textbook ones.
What history says for this winter
History layer · U.S. statesWhere the strong El Niño winters landed
December–February, all 48 states, from the 9 strong El Niño winters since 1950. Colour shows how many of them fell in the warm or cold (wet or dry) third of winters once the long-term trend is removed. Select a state for its full history.
Open the full Winter Odds atlas: every month, every state, every strong winter →
The route board
What is open, what is being pavedEvery product on this site is a numbered route. A route is signed open only once it is genuinely here: no placeholder maps and no invented numbers.
ROUTE 01Open
Now
Every ENSO index side by side, CPC's status, the record watch and the Copernicus forecast, refreshed daily.
CPC · PSL · PMEL · ERA5 · C3S
ROUTE 02Open
ENSO Stripes
Every month since 1940 as a red or blue stripe, every El Niño and La Niña labelled, and the forecast at the end.
ONI 1950→ · MEI-ERA5 1940→
ROUTE 03Open
The Horse Race
This event against 1957, 1972, 1982, 1997, 2015 and 2023, aligned month by month, on the index you choose.
ONI · RONI · MEI-ERA5 · ERA5 Niño-3.4
ROUTE 04Open
U.S. Winter Odds
State by state, month by month: where every strong El Niño winter since 1950 landed, with hit rates, intervals and a false-discovery test.
nClimDiv · n = 9 strong winters
ROUTE 05Open
The Wire
The headline number, every index and the state odds as open JSON, so reporters, agents and other sites can quote them exactly.
JSON · CORS open · CC BY
ROUTE 06Opens Oct 15
Winter Odds: the Season Book
Station-by-station odds for snow, degree days, cold and precipitation at 52 cities, rebuilt from RCC-ACIS daily data, frozen before the season and scored in April.
ACIS ThreadEx · 52 stations
ROUTE 07Open
The ENSO Wheel
Equatorial heat content against Niño-3.4 since 1980: every event as a recharge–discharge loop, and how much fuel this one has left.
PMEL WWV · OISST
ROUTE 08Open
Trajectory
The last three years plus each of SEAS5's 51 members, matched against every path since 1940, and what the winter after looked like.
MEI-ERA5 · SEAS5 members · LOO skill
ROUTE 09Open
Every Strong Winter
The U.S. map of each strong El Niño winter since 1950 side by side, at the detail of 344 climate divisions: the honest antidote to one averaged composite.
nClimDiv divisions · 9 winters
ROUTE 10Open
Event cards
Every El Niño and La Niña since 1940 on MEI-ERA5: its path, peak, length and integrated intensity, and the U.S. winter it brought, division by division.
MEI-ERA5 · nClimDiv divisions
ROUTE 11Open
The world
What El Niño, La Niña and nine other drivers do to rain and temperature in 237 countries, season by season from onset to the year after, with hit counts, intervals and the people under each signal.
GPCC 1891→ · ERA5 1940→ · 13 models
ROUTE 12Open
Your county
For any of 3,107 counties: every strong El Niño winter, the 2026–27 odds with the trend split out, and how much skill that history has had there, tested winter by winter.
nClimDiv counties · LOO skill
ROUTE 13Open
Trajectory Explorer
Draw where ENSO goes through the 2027–28 winter, a fast flip to La Niña or a second warm year, and see what the winters after similar paths since 1940 did to the U.S.
MEI-ERA5 · SEAS5 · 344 divisions
ROUTE 14Open
Drought and pluvial debt
The precipitation every county owes, or has banked, since the La Niña years began, how deep the hydrological drought runs, and how much a strong El Niño winter has historically repaid.
nClimDiv counties · PHDI
ROUTE 15Open
The El Niño-ness Meter
Every day, how closely the last 30 days of U.S. temperature and precipitation match the pattern strong El Niño winters leave, against what past strong El Niño months scored.
PRISM via ACIS · 344 divisions
ROUTE 16Verification open
The model layer
Ten Copernicus systems calibrated on their 1993–2016 hindcasts for every division, county and book station, scored against history and blended by skill. Probabilities publish from Nov 5.
C3S · leave-one-year-out · reliability gate
ROUTE 17Open
The stratosphere
Every sudden stratospheric warming since 1959, the odds by El Niño and the QBO with their uncertainty, and what a vortex breakdown did to the El Niño winters it struck.
ERA5 · SSW catalogue · QBO · polarvortex.earth
ROUTE 18Paving · later
Atmospheric rivers
Landfalling atmospheric rivers by ENSO phase since 1940, and AR lines in the Season Book.
tARget v4 · ERA5 IVT
ROUTE 19Open
The planet: 2027 and CO₂
2027 is the year this El Niño lands on the planet: the odds of a record in four datasets, the 3–5-month lag, the CO₂ growth spike, and every year after a strong El Niño.
ERA5 · NOAA · HadCRUT5 · GISTEMP · Mauna Loa
ROUTE 20Open
The year after
2027 season by season, by state and division, after the 8 strong El Niños since 1950, split by whether La Niña followed.
nClimDiv · PDSI · degree days · n = 8
ROUTE 21Open
Hurricanes
El Niño's calm Atlantic and busy Pacific since 1950, U.S. landfalls, the Atlantic's own warmth, the year after a strong El Niño, and 2026 to date.
HURDAT2 · IBTrACS · ERA5 MDR SST
ROUTE 22Open
Tornadoes and hail
Does El Niño quiet the southern tornado spring? Every January–May since 1950, EF1+, trend removed, with hit counts and a state map.
SPC tornado and hail database
ROUTE 23Open
Sectors
How El Niño reaches energy, farms, water, storms and snow, with a confidence table that puts this site's own hit counts beside the literature.
Hub · 5 sector routes
ROUTE 24Open
Energy
Heating degree days by census division in every strong El Niño winter, the 1997–98 case, the 2026–27 spread, and end-of-March gas storage.
nClimDiv HDD · EIA storage
ROUTE 25Open
Agriculture
Winter wheat moisture odds across the southern Plains, and the Corn Belt summer after, split by whether La Niña followed.
nClimDiv divisions · NCEI crop regions
ROUTE 26Open
Water and snow
April 1 snowpack at 1,358 long-record Western sites, early melt, and California's water year with 1982–83, 1997–98 and 2015–16.
NRCS SNOTEL · snow courses · CDEC
ROUTE 27Open
The archetype library
Every ENSO path since 1940 sorted by stated rules into archetypes (whiplash, double dip, lingering warm…), with U.S. winters for each year of each sequence.
MEI-ERA5 · 344 divisions
ROUTE 28Open
The 2027–28 transition watch
A live watch on the record El Niño's heat reservoir and its track record, beside the models and history on La Niña in 2027–28, unblended, with n everywhere.
PMEL WWV · CPC · SEAS5 · history
ROUTE 29Open
The Hovmöller Wall
The equator day by day since Jan 2025: sea temperature, low-level wind, cloud and ocean heat side by side, every westerly wind burst found by one rule, and 1997 and 2015 at the same stage.
OISST · Reanalysis 1 + GFS · OLR CDR · GODAS
ROUTE 30Open
The Pacific Cutaway
A slice down through the equatorial Pacific, 0–400 m: the thermocline flattening and Kelvin waves pushing east, month by month or every 5 days, against 1997 and 2015.
GODAS · 1991–2020 base
ROUTE 31Open
The I-10 Storm Track
Santa Monica to Jacksonville, milepost by milepost: 2026–27 odds, every strong El Niño winter, the drought debt and the skill along the road.
TIGER roads · 73 counties · LOO skill
ROUTE 32Open
The scorecard
Every test the site has run on itself, the good and the bad, and the Winter Scorecard that grades 2026–27 on April 1.
RPSS · Brier · reliability
ROUTE 33Open
Learn
How a super El Niño is born, in diagrams you can step through, and how to read the odds, intervals and sample sizes on this site.
Explainers · glossary · 24 references
ROUTE 34Open
Event histories
Every El Niño and La Niña since 1940, one page each: its path, its ranks, the U.S. winter it brought, the stratosphere, and what came next.
MEI-ERA5 · ONI · RONI · 43 events
ROUTE 35Open
Embed
The headline ENSO number and the winter odds by state as widgets for your own page.
iframe · 320–600 px
ROUTE 36Open
Country by country
Every country's ENSO year, every event since 1896, the year after, the decades, the other drivers and what 13 models say, one page each.
237 countries · population-weighted
ROUTE 37Open
26 regions, every event
Zeke Hausfather's 26-region table recomputed (179 of 208 against his 176 of 205), the long record back to 1896–97, and which calls survive losing one event.
GPCC V2025 · leave-one-event-out
ROUTE 38Open
The compound ledger
What the La Niña years left behind in every reservoir that remembers: rain, root-zone soil, snow, aquifers (GRACE), drought area and the big reservoirs, and how much a strong El Niño has ever repaid.
ERA5-Land · GRACE · USDM · USBR · CDEC
ROUTE 39Open
Compounding pathways
Fourteen ways El Niño's impacts chain over months and years (whiplash, fuel and fire, snow to summer water, crops to prices, the canal, the anchoveta), each with its evidence and our own numbers.
Literature · World Bank · FAO · NIFC
ROUTE 40Open
Intelligence briefs
Fifteen regions, from the Southern Plains to the Horn of Africa: where each stands on the 2020–2027 path, its reservoirs, what this El Niño usually does, the year after, and what to watch.
Every sentence graded · updated with the site
ROUTE 41Open
How predictable is the compounding?
For 15 regions and 11 compound outcomes: what ENSO, the ground's memory and SEAS5 can predict, how far ahead, scored on years the forecast never saw.
SEAS5 1981–2025 · 9,290 tests · FDR
ROUTE 42Open
Why multi-year matters
The case for planning across ENSO regimes, not single winters: crops, prices, insurance, winter, heat and energy, with the site's own tests and 140 checked papers.
Regimes 1950–2027 · FAOSTAT · RMA · NCEI
ROUTE 48Open
Fall/winter 2026–27 in context
The record El Niño after the La Niña years and a negative PDO: analogs, official guidance and an outlook graded by confidence.
CPC · IRI · BoM · analogs · 29 items
ROUTE 43Open
Agriculture
Yields by regime, and maize breadbaskets failing together in multi-year La Niña.
FAOSTAT · USDA NASS
ROUTE 44Open
Commodities
Grain, softs, palm oil and gas prices after regime onsets, with n and no forecasts.
World Bank Pink Sheet
ROUTE 45Open
Insurance and catastrophe
Crop insurance by cause, hurricanes and severe storms, and the null billion-dollar-disaster result.
USDA RMA · NCEI · HURDAT2
ROUTE 46Open
Winter and energy
El Niño after multi-year La Niña, the PDO's damping, stratospheric warmings, snow and energy.
nClimDiv · ERA5 · stratosphere
ROUTE 47Open
Heat
Summers after El Niño, cooling demand and the record years.
nClimDiv CDD · ERA5 · global