What the UN weather agency's most emphatic Pacific forecast on record actually says about heat, flood and drought risk over the next 18 months — and what it deliberately does not say about any single country.
A very strong El Niño is now effectively locked in for the months ahead, according to a 3 September 2026 update issued from Geneva by the World Meteorological Organization (WMO), which puts the likelihood of the event persisting through to February 2027 at “nearly 100%”. The agency says the pattern is already firmly established, is being fed by exceptionally warm water across the tropical Pacific, and is expected to intensify further before peaking towards the end of this year — with knock-on effects on rainfall, temperature and extreme weather continuing well into 2027.
What makes the update notable is not only the forecast but the confidence behind it. The WMO says this is the first time one of its El Niño/La Niña Updates has been so unequivocal, a reflection of unusually close agreement across its network of Global Producing Centres, national weather services and climate prediction centres.
The Forecast Language That Has Not Appeared in a WMO Update Before
WMO’s seasonal outlooks are built on a consensus of model runs rather than a single agency’s view, which is why the phrasing matters. Previous updates have typically been framed in probability ranges; this one describes an “exceptionally high likelihood of nearly 100%” that El Niño continues into February 2027.
The agency lists five core messages: El Niño is firmly established; it is expected to strengthen further; persistence through February 2027 is near-certain; exceptionally warm tropical Pacific conditions support further intensification; and a very strong event can shift rainfall and temperature patterns worldwide while fuelling extreme weather. Alongside that, WMO and national meteorological and hydrological services say they are stepping up preparedness and early-warning work.
Niño 3.4 Has Climbed From +1.5 °C to as High as +2.6 °C
The clearest evidence in the update is the sea surface temperature record for the central-eastern equatorial Pacific — the region at the heart of the phenomenon. The widely used Niño 3.4 index has strengthened sharply over the course of the northern summer.
| Period | Niño 3.4 sea surface temperature anomaly |
|---|---|
| May–July 2026 (average) | +1.5 °C above normal |
| July 2026 | +2.0 °C above normal |
| Late July to mid-August 2026 (weekly values) | Approximately +2.2 °C to +2.6 °C above average |
More striking still is what is happening below the waterline. WMO reports that in some areas subsurface ocean temperatures ran more than 8 °C above average during July and early August 2026 — a reservoir of heat that gives the event room to keep building rather than fade.
Taken together, the agency says, surface and subsurface conditions provide strong support for El Niño continuing and potentially strengthening further in the coming months. Mutually reinforcing oceanic and atmospheric signals, plus close agreement between seasonal prediction systems, point to the event lasting at least into early 2027.
“El Niño Is Being Supersized Before Our Eyes”: The Warnings Attached to the Update
UN Secretary-General António Guterres framed the forecast in blunt terms, saying the science “leaves no room for doubt” that the planet is in uncharted waters and that those waters are heating up. He described the world as being in “the danger zone of extreme weather”, and characterised the situation as a race between rising risks and the commitment to act and protect people.
WMO Secretary-General Celeste Saulo noted the irony in the name — El Niño means “boy child” in Spanish — while warning it has the potential to deliver a heavy blow to communities and economies. Drought and flood disruption is already being seen, she said, and those impacts are expected to grow as the event intensifies.
Saulo also pointed to the scale of the institutional response: never before in WMO’s 50-year history, she said, has the organization launched such a major mobilization alongside the national meteorological and hydrological services that issue frontline forecasts and warnings. WMO says it will work with UN and humanitarian partners to supply climate intelligence for disaster management and for climate-sensitive sectors including agriculture, health, energy and water resources.
Why a Very Strong Event Does Not Mean the Same Impacts Everywhere
The update carries an important caveat that tends to get lost in coverage of headline numbers: event strength alone does not determine how severe the consequences will be in any given country or region. Effects vary by location and by season, and can be amplified, muted or reshaped by other climate drivers, including conditions in the Indian and Atlantic Oceans.
That is why WMO has published a complementary Global Seasonal Climate Update that folds El Niño together with those other drivers to produce a more refined picture. For September to November 2026, its multi-model forecasts indicate an increased likelihood of above-normal temperatures across almost all land areas, alongside rainfall patterns showing what the agency calls a pronounced and classic atmospheric response to a strong Pacific El Niño.
Two other signals are in play over the same window:
- A positive Indian Ocean Dipole: expected to develop, with a September–October–November 2026 seasonal mean value of 0.9 °C.
- A warm equatorial Atlantic: sea surface temperatures in both the North and South Tropical Atlantic are forecast to stay above normal.
These conditions may reinforce, weaken or alter typical El Niño impacts depending on the region. WMO’s probabilistic temperature and rainfall maps for the season use a 1993–2009 baseline and show the most likely tercile category rather than a single deterministic outcome — a distinction worth keeping in mind when regional forecasts are summarised in a single sentence.
What the Update Does Not Break Out for Canada
The WMO release is a global product and does not issue country-level warnings. For Canadian readers, the practical point is that this update is the upstream input feeding national and regional seasonal outlooks, not a substitute for them. WMO states plainly that national meteorological and hydrological services remain the authoritative source of official warnings and locally relevant climate information, with additional detail delivered through WMO Regional Climate Centres and Regional Climate Outlook Forums.
As general context rather than a WMO finding: seasonal ENSO signals are one of several inputs Canadian forecasters weigh, and their local expression depends heavily on how the mid-latitude atmosphere responds in any given winter. Readers tracking the longer-term backdrop may also want the domestic picture set out in Canada’s Changing Climate Report 2026, which deals with structural warming trends rather than a single seasonal event.
The sectors WMO names — agriculture, energy, water and health — are also the ones where a strong seasonal signal tends to show up in commodity and price forecasts. That overlaps with the kind of uncertainty already flagged in the Bank of Canada’s decision to hold its policy rate at 2.25% as tariffs and oil clouded the outlook, where energy and input costs were central to the discussion.
How ENSO Works, and Why the Peak Is Not the End of It
El Niño and La Niña are the opposite phases of the El Niño–Southern Oscillation, one of the most powerful naturally occurring climate patterns on Earth. El Niño itself is defined by warming of ocean surface temperatures in the central and eastern equatorial Pacific.
- Frequency: typically every two to seven years.
- Duration: around nine to twelve months.
- Development window: generally begins between March and June.
- Peak intensity: usually reached between November and February.
- Lagged effect: the influence on global temperatures can extend beyond peak ocean warming and is often most pronounced in the year after development.
That lag is the reason the current update reaches into 2027 rather than stopping at the turn of the year. Because El Niño can reshape weather thousands of kilometres from the tropical Pacific, WMO argues that reliable forecasts buy governments, humanitarian agencies, businesses and communities time to act before impacts arrive.
The Measurement Debate: From ONI to the Relative Oceanic Niño Index
Since the 1980s, the dominant way of identifying El Niño has been the Oceanic Niño Index, calculated from sea surface temperature anomalies in the Niño 3.4 region and averaged over three months. In recent years, with global ocean warming raising the baseline, a newer metric known as the Relative Oceanic Niño Index (RONI) has gained ground.
RONI measures relative rather than absolute warming, which helps scientists judge whether a warming event is genuinely ENSO-driven or largely a product of broader ocean warming. It is a technical distinction with real consequences for how future events are classified and compared against the historical record.
The update is explicit on one related point: El Niño is a natural climate phenomenon and is not caused by climate change, even as it unfolds against a warming ocean background. WMO says its members and partners will keep monitoring the event closely and will issue regular updates on its likely regional impacts.
Frequently Asked Questions
How long is this El Niño expected to last?
WMO forecasts a near-100% likelihood that it persists through February 2027, with intensification expected in the coming months and a peak towards the end of 2026. Climate impacts are expected to continue well into 2027.
What counts as a “very strong” El Niño in this update?
The update points to Niño 3.4 sea surface temperature anomalies rising from +1.5 °C in May–July 2026 to weekly values of roughly +2.2 °C to +2.6 °C by mid-August 2026, supported by subsurface temperatures more than 8 °C above average in some areas.
Does a stronger event automatically mean worse weather in a given country?
No. WMO states that event strength alone does not determine severity of impacts locally; effects vary by location and season and can be modified by other drivers such as the Indian Ocean Dipole and Atlantic sea surface temperatures.
Where should readers go for official warnings?
WMO identifies national meteorological and hydrological services as the authoritative source for official warnings and locally relevant climate information, with regional detail from WMO Regional Climate Centres and Regional Climate Outlook Forums.
Is El Niño the same thing as climate change?
No. The update describes El Niño as a natural climate phenomenon that is not caused by climate change, though it is occurring alongside rising sea surface and global temperatures.
