A record El Niño on top of a La Niña decade and a cold North Pacific.
The El Niño building now is forecast to be the strongest on record: the C3S multi-system mean for Nov–Jan Niño-3.4 is – (relative index –), and CPC gives a – chance that its relative index is very strong in Nov–Jan (median peak –). It arrives after – La Niña winters in the last six on the relative index (– on the traditional ONI), with the PDO negative in – months since January 2020 (NCEI ERSSTv5; August –, – in CPC's own product), an Indian Ocean Dipole forecast strongly positive but not yet declared, and a westerly QBO. No winter in the record combines all of that. This page sets out what the closest ones did, what the official forecasters say, and what can and cannot be said with confidence.
History here is history, not a forecast: the analog set is six winters, each with its own weather, and 2026–27 is forecast stronger than every one of them. Confidence tiers are the research synthesis's (see the outlook); “our record” grades what this site's own tests show.
The regime as it stands
2014–15 to 2026–27The last thirteen winters, and this one
The same regime timeline as the impacts case, zoomed in: the 2020–23 triple-dip La Niña, the 2023–24 El Niño that followed it, the weak La Niña winters of 2024–25 and 2025–26 (La Niña on the relative index, one neutral on the ONI) and the forecast for 2026–27, with the PDO negative throughout.