El Niño strengthens rapidly: NOAA sees 81% chance of a very strong event by late 2026

El Niño is here, and it is gathering strength fast. In its July diagnostic discussion, the US National Oceanic and Atmospheric Administration's Climate Prediction Center (CPC) confirmed that an El Niño Advisory remains in effect — the alert level indicating El Niño conditions are observed and expected to continue — and said the event will keep strengthening through the end of the year.

What the data shows

In the discussion itself, NOAA reported the weekly Niño 3.4 index — the standard gauge of El Niño strength, measuring sea surface temperature anomalies in the central equatorial Pacific — at +1.2 °C, with the easternmost Niño 1+2 region off Peru and Ecuador running much hotter at +2.7 °C and the western Niño 4 region at +0.5 °C.

CPC's weekly index file tells the same story on its own scale, and it is a story of steady accumulation rather than any sudden jump: Niño 3.4 anomalies climb from about +0.9 °C in late May through +1.5 °C in mid-June to +2.2 °C in the week centred on 22 July 2026, the most recent week published.

Two independent CPC products corroborate that trajectory. The IRI/CPC ENSO Quick Look of 20 July reports the same +2.1 °C for the week centred on 15 July, notes the Niño 3.4 anomaly averaged +0.98 °C over April–June before rising to +1.55 °C in June, and characterises the pattern as "a steady upward trend" rather than any abrupt shift. Readers comparing coverage should be aware that the inline figure quoted in the monthly diagnostic discussion does not always match the weekly index file for the nearest week; where they differ, this site quotes each source for its own number rather than differencing the two.

That mid-year pace matters. El Niño events typically peak around November–January, meaning there are months of strengthening still ahead. NOAA forecasters cited strong coupling between the ocean and atmosphere — the weakened trade winds and shifting rainfall that let an event feed on itself — as the basis for their high confidence.

The probabilities

The joint CPC/IRI outlook attaches numbers to that confidence:

• 100% chance of El Niño conditions for every three-month season from July–September 2026 through January–March 2027;
• 81% chance the event reaches very strong intensity (Niño 3.4 at or above +2.0 °C) during October–December 2026;
• 97% chance El Niño persists through early Northern Hemisphere spring

The IRI's July forecast plume shows all 26 surveyed models — 15 dynamical and 11 statistical — in positive territory, with 23 of the 26 forecasting a very strong event at its peak. The IRI called the signal "clear, consistent, and supported by exceptional model agreement."

"Among the largest in the historical record"

NOAA's forecasters wrote that the developing event "would rank among the largest El Niño events in the historical record going back to 1950." Six events in that record reach the very strong threshold on the Oceanic Niño Index — 1965–66 and 1972–73 (both +2.0 to +2.1 °C), 1982–83 (+2.2 °C), 2023–24 (+2.1 °C), 1997–98 (+2.4 °C) and the record-holder 2015–16 (+2.8 °C) — but only the last three of those are remembered as landmark events, which is a reminder that the index and the impact are not the same thing.

A word of caution on comparisons: weekly values and seasonal averages are different measures. The +2.2 °C figure is a single week's reading; official event rankings use the ONI, a three-month running mean. The event's final place in history will not be known until it peaks.

What happens next

NOAA updates its ENSO outlook monthly, with the next diagnostic discussion due around 13 August 2026. Weekly Niño-region updates are published every Monday. El Niño Monitor will cover each update as it is issued — see our global impacts section for what a very strong event typically means region by region, and the science section for how these forecasts are made.