El Niño tracker: the live index, without the headlines
An El Niño is developing in the Pacific and NOAA expects it to strengthen through winter. Here is the official index, updated weekly — and a straight account of what it does and doesn't shift for a UK winter.
Source: NOAA CPC Oceanic Niño Index and weekly Niño SST indices. Updated 2026-07-24.
Is a "super El Niño" actually coming?
"Super" is press shorthand for a very strong event — the official ONI reaching +2.0°C or above. It hasn't happened yet. The index sits at +0.98°C, which is weak territory, and NOAA hasn't yet declared a formal episode either — that needs five consecutive seasons above +0.5°C and the run currently stands at 2. The weekly readings are running warmer and the trend is clearly upward.
NOAA's ENSO diagnostic discussion of 2026-07-09 put the chance of the November–January peak reaching very strong at roughly 63%. Separately, 23 of 26 models forecast very strong conditions at the October–December peak. Likely, then — but forecast, not observed.
Those outlook figures are from the advisory dated 2026-07-09 and are reissued monthly; the index above updates weekly.
What a strong El Niño shifts for a UK winter
Both of these are tilts in the odds, drawn from a handful of past events. The North Atlantic signal is weak relative to normal winter variability, and UK seasonal forecasts carry real skill only a few weeks ahead.
Tilts milder, wetter and stormier — a stronger Atlantic jet means rain and wind rather than cold. December 2015 fits the pattern, though a record-strong jet and unusually warm Atlantic waters also contributed, so it illustrates rather than proves it.
Research points to a somewhat raised chance of blocked, colder spells via disruption of the stratospheric polar vortex. It is a weak signal, and recent analogues went the other way: both 2015-16 and 2023-24 stayed mild.
A sudden stratospheric warming is the disruption that precedes most of the UK's severe cold outbreaks, including 2018's "Beast from the East". They happen roughly six times a decade — and here is the detail the coverage usually drops: SSWs are not an El Niño speciality. Research finds they become more frequent in both El Niño and La Niña winters compared with neutral ones, and the 2018 event itself occurred during a La Niña. A strong El Niño nudges the odds; it does not create the mechanism.
Every very strong El Niño since 1950 — and what the UK winter actually did
Derived directly from the NOAA ONI record this page tracks: 5 events have reached +2.0°C.
| Event | Peak ONI | What the UK winter actually did |
|---|---|---|
| 1972-73 | 2.12°C | Mild and unremarkable in the UK — no significant cold spell. |
| 1982-83 | 2.23°C | A split winter: very mild, stormy January (6.7°C CET), then a cold, blocked, snowy February (1.7°C CET). |
| 1997-98 | 2.40°C | Exceptionally mild — wet start, very dry finish, no notable cold. February 1998 was among the mildest of the 20th century. |
| 2015-16 | 2.75°C | December 2015 was the UK's warmest December on record and its wettest calendar month since 1910 — storms Desmond, Eva and Frank. The cold never arrived. |
| 2023-24 | 2.06°C | The UK's second-warmest winter on record. Wet and mild throughout; no sustained cold. |
The pattern worth noticing: of the five, four brought the UK mild winters, and the one cold spell (February 1983) followed an exceptionally mild January. One caveat the headlines skip — these are absolute temperature anomalies, and the tropical Pacific has warmed since 1982, so a +2.0°C reading today is not strictly the same event as a +2.0°C reading forty years ago.
We can't tell you in July what February will do, and nor can anyone else — UK seasonal forecasts carry real skill only a few weeks out. What the evidence supports is modest: a somewhat raised chance of a stormy, wet start to winter, and a weaker, less reliable tilt toward a cold spell later on. Sitting underneath both are the ordinary UK certainties — some power cuts, some cold nights, higher heating bills. Prepare for those, before the season, and El Niño can do as it likes.
The sensible preparation (works in any winter)
Common questions
Is there an El Niño right now?
El Niño conditions are present and strengthening — NOAA has an El Niño Advisory active — but the formal episode threshold has not been met yet. NOAA's official Oceanic Niño Index stands at +0.98°C for AMJ 2026, which is weak territory, and a declared episode requires five consecutive overlapping seasons at or above +0.5°C. So far that run stands at 2. The latest single weekly reading is warmer at +2.1°C (week centred 2026-07-15), but weekly values are noisy and NOAA does not classify events on them.
Is a super El Niño coming in 2026-27?
"Super" isn't an official category — it's press shorthand for a very strong event, meaning the ONI reaching +2.0°C or above. It hasn't happened yet: the index is at +0.98°C today. NOAA's advisory of 2026-07-09 put the chance of the November–January peak reaching very strong at roughly 63%, and separately noted 23 of 26 models forecasting very strong at the October–December peak. So it is likely, not certain, and not yet observed.
Does El Niño mean a freezing UK winter?
No — and the record points the other way. El Niño's UK influence is indirect: research suggests early winter tilts milder, wetter and stormier, while late winter carries a somewhat raised chance of blocked, colder spells. But it is a weak shift in the odds against large natural variability, and the last two very strong events (2015-16 and 2023-24) both produced notably mild UK winters. Nobody can forecast a UK February from July.
What happened in the UK during past very strong El Niños?
Mostly mild, which is the opposite of the headline expectation. December 2015 — during the strongest event on record — was the UK's warmest December on record and its wettest calendar month since 1910, with storms Desmond, Eva and Frank. 2023-24 was the UK's second-warmest winter on record. 1997-98 was exceptionally mild. Only 1982-83 delivered a genuinely cold spell, and only in February after a very mild January.
What is the Niño 3.4 index?
It's the sea-surface temperature in a defined box of the central-eastern equatorial Pacific, expressed as a difference from normal. NOAA's official measure, the Oceanic Niño Index, is the three-month running average of that anomaly: +0.5°C or above for five overlapping seasons defines an El Niño episode, and +2.0°C or above is very strong. That patch of ocean is large enough to shift weather patterns worldwide, including the North Atlantic jet stream that shapes UK winters.
What should UK households actually do about it?
Nothing dramatic, and nothing El Niño-specific. The list that pays off in any UK winter, done before the cold rather than during it: know how to keep warm if the heating or power fails, have a carbon monoxide alarm if you burn any fuel, keep a few days of easy food, and lag exposed pipes before the first hard frost. Frozen and burst pipes are the biggest single cause of insured home damage in UK cold snaps — insurers paid around £194m on roughly 86,000 burst-pipe claims after the 2018 'Beast from the East'.
One email if this crosses into very strong
We read the NOAA index every week. If the official three-month figure crosses +2.0°C — the very strong threshold — we'll email once to say so, and once when it falls back. Nothing in between.
Sources: NOAA CPC Oceanic Niño Index, weekly Niño SST indices, and the CPC ENSO diagnostic discussion (2026-07-09) for seasonal probabilities. UK winter context: Met Office monthly climate summaries and the Central England Temperature series; the El Niño/North Atlantic mechanism follows Ineson & Scaife (2009, Nature Geoscience) and Butler & Polvani (2011, GRL) on sudden stratospheric warming frequency in both ENSO phases. Index updated 2026-07-24.