New York, 23 September 2026
Countries and communities across the world must take action now to prepare for increased health risks due to the strengthening El Niño, which is set to trigger more extreme heat, flooding and drought.
El Niño is forecast to intensify into a very strong event by the end of the year, with cascading impacts on economies and societies, according to the latest update from the World Meteorological Organization (WMO). The effects are already visible in climate-sensitive sectors such as health.
“This El Niño is a test. We have the science. We have advance warning. And we still have time to act,” said WMO Secretary-General Celeste Saulo at an event during the United General Assembly in New York.
“El Niño begins with warming in the tropical Pacific, but its consequences are not limited to the Pacific. Thousands of kilometres away, El Niño can shift rainfall patterns and increase the likelihood of extreme temperatures. In cities already struggling with heat, the effects reach inside homes, workplaces, schools and hospitals,” she told the event on Urban Heat Resilience.
Celeste Saulo called on governments, health authorities and community organizations to work with meteorological services to “treat extreme heat as the predictable public-health risk that it is.”
WMO is working with partners to strengthen climate services for health. This means building the needed bridges between health and meteorological communities, to ensure that forecasts reach health authorities at the right time, and in the right format to save lives.
As El Niño peaks late in 2026, much of the Southern Hemisphere, southern Africa, South America and Australia will move into their hottest season in the first months of 2027. Their seasonal heat will land on top of El Niño, raising risks of drought, wildfires, smoke and the air pollution that follows.
City dwellers are especially vulnerable because buildings and roads absorb heat during the day and release it slowly at night. This can leave older people, children, outdoor workers, people with chronic illnesses and residents of poorly ventilated housing with little opportunity to recover.
Heat exposure directly impacts the functioning of the human body and can also contribute to death and severe illness by exacerbating cardiovascular, respiratory, renal, metabolic and mental health conditions. In many parts of the world, heat-related illness, respiratory disease linked to wildfire smoke and poor air quality will also be a concern.
Public health analysis
Extreme heat is just one of the risks examined in a new Global Public Health Situation Analysis – El Niño 2026, published by the World Health Organization (WHO), with input from WMO.
The analysis looks at country- and region-specific risks, drawing on WMO’s forecasts to help health authorities anticipate where and when impacts will hit hardest and how to manage these risks through strengthened disease surveillance systems and rapid response.
“This is more than a heat story. WMO’s seasonal climate outlook for September to November points to above-normal rainfall in some regions and drought risk in others. That puts water security, nutrition, and vector-borne disease on the table alongside temperature,” said Armel Castellan, Extreme Heat Advisor, WHO-WMO Climate and Health Joint Programme.
“The WMO seasonal outlooks buy us much needed lead time, and that lead time is what lets health authorities look ahead and prepare, rather than repair. If health practitioners can make informed decisions, this can make the difference between losing lives or saving them,” he said.
Warmer temperatures and changing rainfall patterns can increase the spread of diseases carried by mosquitoes, such as malaria, dengue, chikungunya, yellow fever and Zika. In some areas, these diseases may spread into places where they have not traditionally been seen, including higher-altitude regions.
Malnutrition and cholera are among the most serious concerns and are assessed as very high risks in both drought- and flood-affected settings. More than 150 million people are already facing acute food insecurity globally. This number is expected to rise as climate-related shocks disrupt food production and livelihoods.
“El Niño is a significant public health threat, not just a climate phenomenon. It is a risk multiplier, and we expect to see health impacts across the world. However, the most severe impacts will be experienced where climate shocks intersect with weak health systems, limited access to health care, food insecurity, displacement and humanitarian crises,” said Teresa Zakaria, Unit Head for Risk Reduction, Humanitarian Operations and Climate Change at WHO.
Source – WMO
El Niño is here: WMO Secretary-General Celeste Saulo calls for action on urban heat resilience
New York, 22 September 2026
El Niño begins with warming in the tropical Pacific, but its consequences are not limited to the Pacific.
Thousands of kilometres away, El Niño can shift rainfall patterns and increase the likelihood of extreme temperatures. In cities already struggling with heat, the effects reach inside homes, workplaces, schools and hospitals.
This El Niño comes on the top of an already over-heating planet. WMO’s State of Climate Report for 2025 has confirmed that the last 7 years have been the hottest on record – and just in the last two months, we have seen record-breaking heat across the world. There is no precedent for an El Niño on a climate baseline as we are living in.
El Niño is strengthening
El Niño is firmly established and strengthening rapidly. WMO forecasts indicate a near-100 per cent likelihood that it will persist through February 2027. It is expected to become very strong towards the end of this year, potentially reaching the upper end of the historical record since 1950.
But we must be precise. El Niño changes the odds; it does not determine the weather in every city or cause every heatwave. Its influence varies by region and season and the way it interacts with other climate drivers.
Near certainty that El Niño will persist does not mean near certainty about a specific local impact. Global forecasts must therefore be translated by WMO Regional Climate Centres and National Meteorological and Hydrological Services into information that cities and communities can use.
Cities must act – Need for coordination
Our cities authorities and governments should act before temperatures reach dangerous levels.
Meteorological services, health authorities, emergency managers, utilities and community organizations should agree in advance on three things: what forecast threshold will trigger action, who will act and who must be reached first.
In a dense city, buildings and roads absorb heat during the day and release it slowly at night. This can leave older people, children, outdoor workers, people with chronic illnesses and residents of poorly ventilated housing with little opportunity to recover.
During this summer’s record-breaking heat, emergency rooms in Paris reported a fourfold increase in heat-related visits. France alone saw over 8000 excess deaths. Belgium, the Netherlands and the UK also reported significant spikes in mortality.
And a staggering 97 of the world’s hottest cities in May 2026 were located in India, where a brutal heatwave pushed temperatures above 45°C in many cities .
But extreme heat is about more than tragic headlines on mortality rates. Heat affects every single sector, and every vital system that people depend on. A heat warning must therefore trigger practical measures: targeted health advice, checks on isolated people, safe cooling spaces, protection for outdoor workers, and continuity plans for electricity, water and health services.
Temperature alone does not tell us who will be harmed. Impact-based warnings connect the hazard with exposure and vulnerability: who is at risk, where and when—and what they should do.
Forecasts and warnings are essential, but the work doesn’t end there. We also need stronger governance for long-term heat resilience. The Extreme Heat Risk Governance Framework and Toolkit that WMO, UNDRR and Global Heat Health Information Network developed together with dozens of governments and experts globally, offers authorities a concrete set of tools to coordinate across sectors and levels of government.
When we strengthen governance, we strengthen preparedness for extreme heat, while reducing vulnerability.
Just as a forecast that does not trigger action is an unfinished service, a government or city without strong heat governance is never fully prepared.
Close the gap – Invest in NMHSs
We must close the gaps across the entire climate services chain, from observation to action across sectors. Heat hits all the systems we rely on at once – our need for health care, cooling, water, transport. The demand for energy that keeps our cities going peaks, just as heat weakens the very systems that provide it.
Investing in National Meteorological and Hydrological Services, reliable observation networks and warning systems that reach the last mile and the last person, is no longer optional.
It means making our cities safer: better-ventilated homes, shaded public spaces, urban trees, reflective roofs and surfaces, and essential systems and services that continue operating during extreme heat.
Technology and finance should address real operational needs: better observations, interoperable data, dependable alert delivery, resilient power and affordable cooling. The test is not how sophisticated a tool appears. The test is whether it helps a city act earlier and protects people who might otherwise be missed.
My final message to the leaders gathered here is to treat extreme heat as the predictable public-health risk that it is.
Identify who is most exposed. Agree the triggers for action with meteorological and health services. Make sure warnings reach people in time and in language they understand.
This El Niño is a test. We have the science. We have advance warning. And we still have time to act.
Rather than make excuses for why our knowledge did not become action, let us use that time to prepare and protect our cities and their residents.
Source – WMO