A very strong El Niño is forecast. Its local effects still need a map.

A farmer deciding when to sow rice, a water manager watching a depleted reservoir and an emergency agency preparing for floods may all be responding to the same El Niño. They should not expect the same weather.

Measurements show an unusually powerful event developing in the tropical Pacific. The practical warning, however, is not “extreme weather everywhere.” It is that familiar rainfall and temperature patterns are becoming more likely to shift—and that regional forecasts and conditions on the ground must determine the response.

What has actually been observed

By mid-August, El Niño was firmly established, according to the World Meteorological Organization. Its multi-centre forecasts put the probability of the event persisting through February 2027 at nearly 100%.

NOAA’s September assessment adds the measurements behind that diagnosis. Surface water in the eastern equatorial Pacific was more than 3°C above average in places, while the widely watched Niño-3.4 region was 1.8°C above average. Winds, rainfall and atmospheric pressure had also shifted in a pattern consistent with El Niño. That last point matters: El Niño is not merely a patch of warm water but a coupled change in the ocean and atmosphere.

NOAA gave a greater than 90% chance that the event would become “very strong” during the Northern Hemisphere autumn and winter. Its official strength table put the chance of the three-month October–December index reaching at least 2°C above its 1991–2020 baseline at 98%.

A separate figure in NOAA’s diagnostic discussion—a 75% chance of an October–December value of at least 2.5°C—answers a stricter question. The percentages are not competing estimates: one concerns entry into the very-strong category, while the other concerns crossing a higher, potentially record-setting threshold.

One Pacific event, several regional forecasts

Warm equatorial Pacific water reorganizes tropical rainfall and winds. Those changes can influence weather far away, but geography, season and other ocean patterns shape where the effects appear.

Australia’s September outlook illustrates the uneven result. The Bureau of Meteorology forecast below-average spring rainfall in parts of the south and east, yet above-average rain across much of the west. It also expected unusually warm days and nights across large areas. The bureau cautioned that El Niño is only one of several influences; it was also monitoring the Indian Ocean Dipole and unusually warm surrounding seas.

Across the Greater Horn of Africa, the regional signal pointed in another direction. ICPAC forecast a 90% chance of enhanced October–December rainfall over southern Ethiopia, central and southern Somalia, and northeastern Kenya. That season supplies a large share of annual rain in parts of the region, making the forecast consequential—but still probabilistic. ICPAC directed decision-makers to continuing national, weekly and shorter-range updates.

Southern Africa, meanwhile, received a consensus outlook favouring drier conditions across much of the region. FAO reported that planners were matching that outlook with crop calendars, livelihood data and possible triggers for seed, livestock, water and cash support. Forecasters also warned that a dry season overall would not rule out a flash flood or cyclone.

The forecast becomes useful when it meets local evidence

In Malaysia’s Kedah state, the relevant signal is not the global El Niño label alone. Three reservoirs serving the Muda agricultural area held a combined 35.76% of capacity in mid-September, according to reporting based on the local water authority. Officials set phased sowing dates for 99,489 hectares and deployed drainage-water recycling and mobile pumps. Observed storage, expected rainfall and the crop calendar together produced an operational decision.

FAO uses a similar combination at larger scale. Its agricultural risk mapping draws on 41 years of satellite records to locate crop and pasture areas historically susceptible to El Niño-related drought. Exposure and vulnerability then matter: the same rainfall deficit can have very different consequences depending on irrigation, conflict, existing hunger, livestock dependence and households’ capacity to absorb a loss.

A simple way to read any El Niño warning is to ask four questions:

1. What is observed? Look for measured ocean temperatures and accompanying atmospheric changes.
2. What is forecast? Separate the probability of El Niño continuing or strengthening from the probability of regional rain or heat.
3. What is exposed now? Check reservoirs, soil moisture, crop calendars, infrastructure and existing hardship.
4. What would trigger action? A seasonal forecast may justify preparation; planting changes, aid releases or evacuations usually require more local information and updated forecasts.

The same discipline applies afterward. A flood, drought, failed harvest or price increase may be consistent with El Niño without being proved to have been caused by it. Establishing causation requires evidence about the event itself, competing influences and the mechanism connecting Pacific conditions to that particular outcome. El Niño’s strength improves the warning signal; it does not turn a planetary climate pattern into a local weather script.