NOAA Warns El Niño Could Become Historic in 2026, With Italy Bracing for Autumn Impacts

On August 13, 2026, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC) reported that El Niño is strengthening rapidly, with a greater than 90% chance of a very strong Northern Hemisphere fall-winter 2026–27 event and a 69% probability of reaching historic intensity — exceeding every El Niño episode recorded since 1950. The advisory triggered widespread coverage across Italian media, where outlets including RaiNews, Sky TG24, and L’Espresso examined how the intensifying Pacific pattern could shape Italy’s autumn 2026 climate.

Editor’s note: This article draws on NOAA CPC’s August 13, 2026 ENSO Diagnostic Discussion, U.S. weather agency reporting, and Italian outlet coverage cited in international media, August 13–24, 2026. CPC issues updated ENSO discussions monthly; the next is scheduled for September 10, 2026.

What NOAA reported on August 13

The CPC placed the ENSO Alert System at El Niño Advisory status. Its monthly diagnostic described a coupled ocean-atmosphere system that has been strengthening for weeks:

Indicator	July 2026 reading
Niño-3.4 (key ENSO index)	+1.4°C above average
Niño-3	+1.7°C
Niño-1+2 (eastern Pacific)	+2.9°C
Subsurface temperature anomalies	Up to +10.0°C at depth
Sea surface anomalies (eastern Pacific)	Exceeded +2.0°C

Low-level westerly wind anomalies and upper-level easterly wind anomalies stretched from the western to east-central equatorial Pacific. Convection and rainfall were enhanced from the central to eastern Pacific and suppressed over Indonesia. Traditional and equatorial Southern Oscillation indices were significantly negative — near two standard deviations during July.

The CPC’s official ENSO outlook, which blends models from North America and abroad, projects El Niño will continue strengthening through the end of 2026.

What “historic” means in this forecast

For the October–December 2026 season, CPC assigned a 69% chance that El Niño would become a historic event — defined as a three-month Relative Oceanic Niño Index (RONI) value of +2.5°C or higher, surpassing the strength of any El Niño since record-keeping began in 1950.

That threshold sits above the CPC’s “very strong” classification. The agency noted that with an event of this magnitude, the likelihood of impacts consistent with El Niño grows — but impacts are not guaranteed for every region. Seasonal anomaly probabilities are published separately in CPC outlook products.

NOAA also raised the probability of a very strong fall-winter event to above 90%, up from an 81% estimate in its July outlook — underscoring how quickly conditions evolved over a single month.

Why Italian outlets are paying attention

Italy does not sit on the Pacific rim, so El Niño’s direct impacts are indirect. Italian broadcasters and newspapers nonetheless devoted significant coverage after the August 13 advisory, focusing on how altered global atmospheric circulation can reach the Mediterranean.

Outlets cited by international reporting highlighted several plausible autumn pathways for Italy:

• Warmer-than-average conditions — El Niño tends to elevate global mean temperatures; central Pacific surface temperatures had already surpassed prior records for 75 consecutive days as of mid-August and could rise further by December.
• Persistent subtropical anticyclones — Strong, long-lasting high-pressure systems over Italy during summer and early autumn, sustaining heat and humidity.
• Alternating extremes — Very hot spells followed by episodes of severe instability, cloudbursts, and heavy rainfall — a pattern sometimes described as weather “swinging” between extremes rather than settling into one regime.

RaiNews and other Italian sources stressed that exceptional El Niño intensity increases the odds of extreme weather but does not allow precise prediction of where or what type of events will occur.

Global context beyond Italy

The August 13 discussion fits into a broader 2026 climate picture:

Atlantic hurricane season

NOAA’s updated 2026 Atlantic hurricane season outlook cited a very strong El Niño as a primary driver behind an expected below-average Atlantic hurricane season. El Niño typically increases upper-atmospheric wind shear over the Atlantic, suppressing storm development. Scientists cautioned, however, that a record-breaking El Niño could produce atmospheric responses not seen in prior events — making historical analogs less reliable.

Pacific and tropical impacts

Regions bordering the Pacific historically bear the brunt of El Niño: altered rainfall patterns, marine heat stress, fisheries disruption, and increased flood or drought risk depending on latitude. The eastern equatorial Pacific’s +2.9°C Niño-1+2 reading and deep subsurface warmth signal a large ocean heat reservoir that could fuel further intensification through late 2026.

Europe’s indirect exposure

For Europe broadly, El Niño’s fingerprint is subtler than in the tropics but still measurable through shifted jet-stream behavior and modified pressure patterns. Italian meteorologists and climate writers emphasized that autumn 2026 planning — agriculture, water management, energy demand — should account for elevated uncertainty rather than a single fixed forecast.

How El Niño is defined

NOAA defines El Niño as a phase in which equatorial Pacific sea surface temperatures remain at least 0.5°C above the climatic average for roughly five consecutive months. The current episode has moved well beyond that baseline, with multiple indices already in strong territory and models projecting further gains.

The phenomenon arises from a coupled interaction between warmer ocean waters in the central and eastern tropical Pacific and atmospheric circulation changes — the Southern Oscillation — that reinforce each other. La Niña represents the opposite cool phase; neutral conditions sit between them.

What comes next

The CPC schedules its next ENSO Diagnostic Discussion for September 10, 2026. Weekly updates on equatorial Pacific conditions are published on the CPC website. Italian and international outlets are expected to revisit autumn forecasts as new model runs incorporate August ocean data.

For residents and policymakers in Italy, the August 13 advisory is less a precise weather forecast than a risk signal: a historically strong El Niño raises the probability that autumn 2026 will bring sustained warmth, volatile swings between heat and storms, and conditions that differ from a typical Mediterranean fall.

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Discussion

1. How should Italy prepare for an autumn shaped by a potentially historic El Niño?

Water reserves, crop planning, and urban heat planning all hinge on seasonal expectations. Does a 69% probability of record intensity justify early contingency measures, or is that still too uncertain to act on?

2. Does a strong El Niño make individual extreme events feel more predictable — or less?

CPC warns that greater intensity widens the range of possible impacts without guaranteeing any single outcome. When headlines say “historic,” do readers overestimate how much local weather can be forecast?

Share how you read climate advisories — and whether autumn 2026 already feels different where you live.