El Niño is not a forecast toy this autumn — it is already roaring. CPC’s Sept. 10 diagnostic discussion, still the controlling monthly outlook heading into early October, placed the system under an El Niño Advisory and said the event is strengthening further. Sea-surface temperature anomalies exceeded +3.0°C in the eastern equatorial Pacific. Niño-3.4 sat near +1.8°C, Niño-3 near +2.5°C, and Niño-1+2 near +3.4°C, while subsurface waters ran more than 10°C above average at depth across wide stretches of the basin.

CPC’s official outlook, blending North American and international models, shows El Niño continuing to strengthen through year-end. For October–December 2026, forecasters put a 75% chance on a historic-strength event exceeding +2.5°C on the relevant three-month index — stronger than prior events back to 1950 in that framing. Greater than 90% odds attach to a very strong event lasting through fall and winter 2026–27. Atmospheric signs match: low-level westerlies, enhanced central-to-eastern Pacific rainfall, and suppressed rain over Indonesia.

Impacts are probabilistic, not guaranteed. U.S. winter temperature and precipitation outlooks will shift as the event peaks; coastal communities should watch CPC seasonal maps rather than a single headline. The next ENSO diagnostic discussion is scheduled for Oct. 8. Farmers, utilities, and emergency managers should treat the October CPC outlook refresh as an operational product, not a curiosity headline. Primary documents linked below carry the figures used here. Check those URLs before treating tip-sheet summaries as final. Concrete dates and instrument readings beat vague climate talk.

What we know:
El Niño is strengthening with >90% odds of a very strong fall/winter event; eastern Pacific anomalies have exceeded +3°C.

What we don’t:
Exactly which U.S. regions will see classic El Niño rainfall and temperature anomalies at peak.