El Niño is Here: Time to Act on Urban Heat Resilience
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.
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