El Niño 2026–27 tracker
An El Niño is under way, and NOAA expects it to peak this coming winter. That matters for heat: El Niño is the single biggest natural driver of record global temperatures, and the hottest years on record have landed the year after it peaks. So a strong 2026–27 El Niño is an early warning that summer 2027 could break heat records — this page tracks it with the latest official NOAA numbers, updated monthly, and is honest about what it does and doesn’t tell you about your own weather. If you have seen this same event described as anything from half a degree to four degrees above normal, that is because different sites quote different Pacific regions and different indices; we show all of them from the NOAA files and name the one the official advisory rests on.
In plain English: El Niño isn’t a season — it’s a warm-water pattern in the Pacific Ocean, like a fever that runs hottest in winter. Because the ocean takes months to heat the whole planet, its record-heat effect shows up the following year: a peak in winter 2026–27 is what raises the odds that summer 2027 runs hot, not the winter itself. (NOAA — the National Oceanic and Atmospheric Administration — is the official US science agency for this; its Climate Prediction Center, or CPC, is the primary source everyone else quotes.)
Data as of 2026-07-29. NOAA’s Climate Prediction Center issues its next ENSO discussion on 2026-08-13 — we refresh this page after each update. Source: CPC ENSO Diagnostic Discussion, the ONI data file and the weekly SST table.
Live extreme heat warning map — official sources only
How to read this honestly: El Niño shapes the season's odds — no single alert, fire or heatwave on this map is "caused" by it, and any tracker that says otherwise is overclaiming. What the map shows is the current official picture, fetched live from the sources the moment you open it: every active National Weather Service extreme heat warning, heat advisory and cold alert for the US, significant open events from NASA's EONET worldwide, and the Niño-3.4 ocean region the ENSO index is measured in. A toggle adds NASA's daily sea-surface temperature anomaly imagery — the warm Pacific water that is the El Niño. Click anything for its official source.
Map data © OpenStreetMap contributors · Tiles by OpenFreeMap · Alerts: NWS/NOAA · Events: NASA EONET · ENSO: NOAA CPC · Sea-surface imagery: NASA GIBS
January 2025 to now: 16 rolling ONI readings
The Oceanic Niño Index (ONI) is a three-month rolling average of the sea-surface temperature anomaly in the tropical Pacific. Anything at or above +0.5 °C (the dashed line) is officially El Niño; below −0.5 is La Niña. Read it left (oldest) to right (now), and watch the climb out of La Niña into a strengthening El Niño.
Chart data: NOAA CPC ONI file, pulled 2026-07-29. Values are °C anomaly, oldest (left) to newest (right). Orange bars above the centre line are El-Niño-leaning; blue bars below are La-Niña-leaning. The blue bars on the left are the past La Niña, not a forecast.
How strong is “strong”?
NOAA classifies El Niño by the peak ONI value it reaches. The current event has already crossed into El Niño territory; the open question is how high it climbs this winter.
| Category | Peak ONI (°C) | Where we are |
|---|---|---|
| Weak El Niño | 0.5 to <1.0 | ← current (AMJ 2026) |
| Moderate | 1.0 to <1.5 | — |
| Strong | 1.5 to <2.0 | — |
| Very strong | 2.0 and above | — |
Strength bands: NOAA CPC ONI strengths. A “very strong” event (peak ≥ 2.0 °C) would rank among the largest since records began in 1950.
Why every site gives a different El Niño number
Because they are quoting different indices — and all of them are real NOAA numbers. On week of Jul 22, 2026 the published figures for this one event ranged from +0.47 to +3.8 °C depending on which region and which index you read. Here is every one of them, straight from the NOAA files.
Four regions, four different answers
NOAA measures the tropical Pacific in four boxes. The weekly file publishes all four; almost everyone quotes just one, without saying which.
| Region | Where it is | Anomaly |
|---|---|---|
| Niño 1+2 | far eastern Pacific, off Peru and Ecuador | +3.8 °C |
| Niño 3 | eastern equatorial Pacific | +2.5 °C |
| Niño 3.4 | central-eastern — the region NOAA headlines | +2.2 °C |
| Niño 4 | central-western equatorial Pacific | +1.0 °C |
So when a forecast says this El Niño is “three to four degrees above normal”, that is almost always Niño 1+2 — a small box off the coast of Peru — and not the region the official advisory is based on.
Two indices, same three months
ONI +0.98 (AMJ 2026) — the Oceanic Niño Index, the official measure NOAA declares an El Niño on.
RONI +0.47 (AMJ 2026) — the Relative Oceanic Niño Index: the same measurement with the warming trend of the wider tropics subtracted, so it shows how much this event stands out from its own era.
Read plainly: on the ONI this is an El Niño; on the RONI it has not yet crossed the +0.5 °C threshold. Both indices are published by NOAA’s Climate Prediction Center from the same ocean data. NOAA declares on the ONI, so the El Niño Advisory stands and this page leads with that number. The RONI is the honest second opinion, and it is why the CPC’s own written discussion quotes cooler figures than the raw weekly file.
Regions and weekly values: NOAA CPC weekly SST table (week of Jul 22, 2026). ONI: ONI data file. RONI: RONI data file. Pulled 2026-07-29.
Is this the strongest El Niño on record?
Not so far — and which event holds the record depends on which index you use. On the ONI, 2014-16 is the strongest since 1950 at +2.75 °C. On the RONI, 1982-83 leads at +2.52 °C. The current event peaks this winter, so it has not been written yet.
| Event | Peaked | ONI peak | RONI peak |
|---|---|---|---|
| 1972-73 | NDJ 1972 | +2.12 | +2.27 |
| 1982-83 | NDJ 1982 | +2.23 | +2.52 |
| 1991-92 | DJF 1992 | +1.71 | +2.32 |
| 1997-98 | OND 1997 | +2.40 | +2.38 |
| 2009-10 | NDJ 2009 | +1.56 | +1.56 |
| 2014-16 | NDJ 2015 | +2.75 | +2.37 |
| 2023-24 | NDJ 2023 | +2.06 | +1.49 |
Read the last two columns against each other and a pattern shows up: events before 2000 score higher on the RONI than the ONI, and events since 2014 score lower. As the whole tropical ocean warms, an anomaly measured against a fixed baseline makes a recent event look larger compared to the ocean around it. The sharpest example is 2023-24: +2.06 on the ONI (very strong) but +1.49 on the RONI (below strong). That is the single best reason to treat “strongest ever” headlines carefully.
“Super El Niño” is not an official category. NOAA’s strength bands stop at “very strong” — a peak ONI of +2.0 °C or above, the table further up this page. The phrase is used widely in forecasting and in the press, but with no agreed threshold: we have seen it defined as +1.5 °C on one site and +2.0 °C on another in the same week. When you see it, check which number is meant before you act on it.
Peaks computed from the ONI and RONI data files on 2026-07-29: contiguous runs of ONI ≥ +0.5 °C lasting five or more overlapping seasons, strong-and-above events only. Published peak values differ between sites — recompute from the files rather than copying them.
What this means — and what it doesn’t
What El Niño reliably does: its clearest, most dependable effects in the United States are in winter, not summer — a jet stream shifted south and east tends to bring a wetter southern tier and Southeast and a milder north. NOAA’s own guidance notes El Niño’s US influence is “weak during the summer and more pronounced starting in the late fall through spring.”
What it does not do: El Niño does not cause your local summer heatwave. Any single heatwave, storm or flood has many causes, and — in NOAA’s words — a single El Niño “increases the odds” of certain patterns rather than guaranteeing them. Beware any tracker that tells you this summer will be hot “because of El Niño.” That’s not how the science reads.
Where El Niño does touch global heat is indirect and lagged: it nudges global average temperature up by roughly 0.07 °C for every 1 °C of Niño-3.4 warming, on a two-to-three-month delay. Because of that lag, the hottest calendar year on record has historically landed the year after a strong El Niño peaks — 1998, 2016 and 2024 all followed that pattern. 2024 was the warmest year since records began in 1850, at +1.29 °C above the 20th-century average.
Keep two signals separate, the way NOAA and the WMO do: the long-term warming trend from climate change is one thing; the year-to-year wobble from El Niño and La Niña is another. El Niño can amplify the impacts of a warming climate, but there’s no evidence it’s becoming more frequent or intense because of it.
Sources: NOAA Climate.gov ENSO blog and FAQ; NOAA NCEI 2024 global climate report; NWS El Niño explainer; World Meteorological Organization El Niño updates. Figures re-verified 2026-07-05.
Questions people actually ask
What is an extreme heat warning?
An Extreme Heat Warning is the National Weather Service's most serious heat alert — issued when dangerously hot conditions are expected or occurring in an area. In 2025 the NWS renamed its top-tier heat alert from "Excessive Heat Warning" to "Extreme Heat Warning"; both names mean the same thing, and the map colors them the same deep red. One tier down sit the orange Extreme Heat Watch (dangerous heat is possible) and the yellow Heat Advisory (hot enough to be risky, especially for vulnerable people). Every alert on the map links to its official NWS zone page — treat that page, not us, as the instruction.
Where does the map data come from, and how fresh is it?
Four official sources, nothing else: NWS/NOAA active alerts (api.weather.gov), NASA EONET open events, NOAA CPC ENSO data, and NASA GIBS daily sea-surface temperature anomaly imagery. The alert and event layers are fetched live from those sources every time the map opens — an alert issued minutes ago appears, an expired one is gone. The stamp under the map states per layer whether you are seeing the live fetch or the built-in backup copy (shown only if a source is briefly unreachable). ENSO values and the news list refresh automatically each week, and the NASA sea-surface imagery is served live at daily resolution.
Does El Niño cause the extreme heat warnings on this map?
No — and that's the point of the framing line above the map. El Niño shifts the odds of seasonal patterns; no single heat warning, fire or storm can honestly be attributed to it. The alerts layer and the ENSO layer are shown together because both shape your summer, not because one causes the other.
Can I use or cite this map?
Yes, freely, with a link — the citation box above the FAQ has a copy-ready reference. If you need the raw data, go straight to the official sources: they publish everything we show.
Why do different websites give different El Niño numbers?
Because they are quoting different indices without saying which. NOAA measures four regions of the tropical Pacific and publishes two seasonal indices, and on the same day they can range from about +0.5 to +3.8 °C for the same event. The number the official advisory rests on is the ONI, a three-month average of the Niño 3.4 region. A headline saying “three to four degrees above normal” is usually quoting Niño 1+2, a small box off Peru. The full breakdown, with every current value, is in the section above.
What is the difference between an El Niño Watch and an El Niño Advisory?
They are the tiers of NOAA’s ENSO Alert System, and they mean different things. An El Niño Watch means conditions are favourable for an El Niño to develop within the next six months — a heads-up, not a declaration. An El Niño Advisory, which is what is in force now, means El Niño conditions are actually present and expected to continue. A Final El Niño Advisory is issued when the event is ending. There is also a La Niña equivalent of each, and “ENSO-neutral” when neither is active.
Is this a “super El Niño”?
There is no official answer, because “super El Niño” is not an official NOAA category. NOAA’s published strength bands stop at very strong, meaning a peak ONI of +2.0 °C or above. The term is common in forecasting and the press but carries no agreed threshold — it is defined as +1.5 °C in some places and +2.0 °C in others. What NOAA has actually said is that there is an 81% chance this event reaches very strong during October to December 2026.
What to actually do about it
Why this matters for heat: a peaking El Niño is the clearest early signal we get that the following summer carries elevated record-heat odds — so the sensible move is to be ready before demand and prices spike, not during a July heatwave. If a strong El Niño winter is coming, the useful response isn’t panic-buying an air conditioner today — it’s ordinary preparedness. If you’re in the wetter southern tier, that means drainage, sump pumps and storm supplies. Everywhere, it means knowing the heat-safety basics for the summer you’re actually in right now.
- How to stay safe in extreme heat — the heat-index bands, when a fan stops helping, and who’s most at risk. Includes a live heat-index checker.
- Cooling gear guides — if you do need to buy, the honest guides to portable ACs, window units and fans.
- Find the cooler that fits your room — answer a few questions about the space and it returns a unit that genuinely fits, or says plainly that nothing we can point you to does.
- Cooling with no mains power — battery-run air conditioners and the power stations that actually carry them, for tents, vans, cabins and outages.