WHO Classifies El Niño Health Impacts as Emergency as India Faces Heat and Disease Risks

India's heat exposure puts health warning into focus

An estimated 146.5 million people in India faced extreme heat during April 2026, while a Himalayan glacier collapse and downstream flash floods killed more than 1,300 people in Nepal in late August, according to the World Meteorological Organization (WMO). Those disasters form part of a wider climate assessment that says the World Health Organization (WHO) has, for the first time, classified the anticipated health impacts of El Niño as a health emergency.

The WMO released its State of Climate Update on November 9, the opening day of COP31 in Antalya, Türkiye. It puts the global average surface temperature for January through September at about 1.47°C above the average for 1850 to 1900, before industrial activity greatly increased greenhouse gas concentrations.

India faces several overlapping threats. WHO identifies high or very high risks involving dengue, leptospirosis and communicable diseases, with malaria risks highlighted in parts of northeast India. Heat, water shortages, damage to crops and interruptions to medical care can make those threats harder to manage.

El Niño is a recurring warming of surface waters in the central and eastern tropical Pacific Ocean. Its effects reach far beyond the Pacific because changes in ocean temperatures alter atmospheric circulation, shifting where heat and rain occur.

WHO's response centres on preparing health services before conditions worsen. Its public health situation analysis, published on September 5, is a technical document of 63 pages prepared by its Health Emergencies, Preparedness and Response team. It supports assessments tailored to individual countries and regions, focusing on vulnerable people and whether health systems are ready.

The practical concern is a chain of pressures: dangerous heat can increase demand for treatment just as drought or flooding interrupts water, electricity, transport and medical supplies.

Why the temperature threat extends into 2027

The WMO says El Niño intensified from August and is expected to reach record strength by December. Its COP31 climate update warns of increased risks of extreme heat, drought and heavy rainfall well into 2027.

WMO Secretary-General Celeste Saulo explained how the phenomenon interacts with an ocean already holding exceptional amounts of heat:

El Niño doesn't add new heat to the planet. It releases heat from the ocean, which is the warmest ever measured. There is simply more heat available to release,

El Niño typically raises annual global average temperatures by around 0.1°C to 0.2°C. Its largest effect on the global annual temperature usually comes in the year after it develops, making 2027 a particular concern.

Saulo's November 9 statement says Pacific sea surface temperatures could reach nearly four times the 0.5°C warming threshold used to declare El Niño between November 2026 and January 2027. That comparison concerns warming in the tropical Pacific; the global temperature figures use a different geographical area and reference period.

The WMO places 2026 among the four warmest years recorded. Its January to September average of 1.47°C is below the full year record of 1.55°C in 2024, though temperatures are expected to rise further before December ends. The final ranking for 2026 is pending, with the complete State of the Global Climate report scheduled for March 2027.

What WHO identifies as India's main risks

WHO's detailed health assessment forecast drier conditions and above average heat across most of South Asia for August through October 2026. Heat stress, food insecurity, malnutrition and worsening chronic illnesses feature among the high or very high risks common across much of the region.

India's disease risks vary by location. WHO lists dengue and leptospirosis among its country concerns, while specifying parts of northeast India for malaria. Leptospirosis is a bacterial infection that can spread through water contaminated by infected animals, making flooding and poor sanitation important concerns.

WHO describes El Niño as a risk modifier: it changes the conditions in which illness can spread or become more severe. Local sanitation, immunity, access to treatment and the strength of disease control programmes help determine what happens in each community.

Delhi had recorded 90 dengue cases during August and a seasonal total of 311 by August 29. Malaria cases increased from 17 in July to 53 in August, more than tripling. Those figures show why local surveillance matters alongside seasonal climate forecasts.

Mosquito risks can increase in different ways. Heavy rainfall leaves standing water where mosquitoes breed. During drought, households may store water in open containers, creating breeding sites close to people. Temperature also affects mosquito survival and the development of the viruses or parasites they carry.

WHO also flags a likely positive Indian Ocean Dipole, a pattern with warmer waters in the western Indian Ocean and cooler waters in the east. It could reinforce dryness in South and Southeast Asia while increasing rainfall and flood risks in equatorial East Africa during October through December.

Heat threatens more than comfort

Extreme heat can cause dehydration, heat exhaustion and heatstroke. It also puts extra strain on people with heart, lung and kidney conditions, diabetes and other chronic illnesses. WHO identifies older people, infants, outdoor workers and socially vulnerable populations as groups facing particular risks.

Pregnancy adds another concern. WHO's assessment cites research associating heat exposure with preterm birth, stillbirth, congenital anomalies and babies born small for their stage of pregnancy. The severity of heat exposure depends on humidity, its duration and whether temperatures fall enough at night for people to recover.

Dr. Arunesh Kumar, senior consultant in respiratory medicine at Paras Health in Gurugram, describes the effects on patients:

Periods of extreme heat can increase the likelihood of dehydration, heat exhaustion and heatstroke, while also placing additional stress on people with existing cardiovascular, respiratory or kidney conditions.

For households, the preventive measures include staying hydrated, reducing prolonged outdoor exposure during peak heat, following local weather advice and maintaining safe food and water practices. Reducing water stagnation around homes and workplaces can help control mosquitoes.

Smoke creates another route to illness. Drought and dry conditions can increase wildfire risks, while fine particles carried by smoke can worsen asthma, chronic obstructive pulmonary disease and cardiovascular illness far from a fire.

Nepal already faces overlapping pollution pressures. A warning about crop smoke reaching Nepal described how winds could carry emissions from Indian farmland into the country while local traffic and waste burning added to exposure. Residents can face several sources of harmful air at once.

Food shortages can become medical crises

WHO rates malnutrition and cholera and other waterborne diseases as very high risks under both warmer, drier conditions and warmer, wetter conditions. Drought can reduce harvests and water available for hygiene. Flooding can destroy crops, damage sanitation and contaminate drinking water.

Families relying on farming that depends on rainfall face a double loss when crops fail: less food to eat and less income to buy replacements. Higher prices can then force households to reduce the quantity or quality of meals. Diarrhoeal illness makes the nutritional damage worse.

Economics professor Eoin McLaughlin of Heriot-Watt University and management professor Matthias Beck of University College Cork examine those connections in their climate and health analysis, published on November 9. They cite South African maize production around 40% below normal during the 2015–16 El Niño and about 20% below normal in 2023–24.

The authors say the UN Food and Agriculture Organization and World Food Programme proposed anticipatory assistance for 8.8 million people. They also describe severe existing pressures: an estimated 57% of Somalia's population and 51% of Haiti's were undernourished, while 63% of South Sudan's population faced severe food insecurity. The figures use different measures, but all point to populations entering another climate shock with limited protection.

McLaughlin and Beck argue that food shortages may also change exposure to infections transmitted from animals to people. When familiar food becomes unavailable or unaffordable, greater reliance on wild meat can increase contact with infected wildlife through hunting and preparation.

Their historical comparison shows why relief systems matter. During the 1876–78 El Niño, failed monsoons, lost incomes and unaffordable food contributed to devastating famines in India and China. Ireland also suffered poor harvests, but food transported by rail and sea, together with aid, helped avert widespread famine.

A global toll, with Nepal facing lasting disruption

Europe's heatwaves, drought and wildfires were associated with more than 30,000 excess deaths, according to preliminary estimates cited by the WMO. Excess deaths are deaths above the number normally expected during a given period. At least eight European countries broke national temperature records, with disruptions to farming, energy and transport.

Nepal's late August glacier collapse and downstream flash floods exposed the danger to settlements below warming mountain terrain. The WMO records more than 1,300 deaths and a major economic impact.

The disruption continued beyond the immediate disaster. After floods disrupted Nepal tourism, October arrivals from India fell to 12,097 from 17,298 a year earlier, a decline of about 30%. Damaged roads and pilgrimage routes affected travel and businesses dependent on visitors.

McLaughlin and Beck cite a Climate Impact Lab projection of 451,000 additional deaths associated with heat from the current El Niño, mainly in countries with low and middle incomes, particularly the Sahel. The figure is a projection of potential losses, while Europe's preliminary excess death estimate concerns impacts already recorded.

WHO's preparedness priorities extend beyond treatment of immediate injuries. Displacement and crowded living conditions can increase disease transmission, while interrupted immunisation and difficulty reaching clinics can leave people exposed to preventable illnesses.

The ocean and water records behind the warning

Greenhouse gases provide the longer term warming pressure behind this El Niño. The WMO says atmospheric carbon dioxide reached about 426.8 parts per million in 2025, up 53% from around 278 in 1750. Methane reached 1,948 parts per billion and nitrous oxide 339.1 parts per billion.

Earth is accumulating heat because more energy enters the climate system than escapes back into space. That energy imbalance reached its highest observed level in 2025 in measurements beginning in 1960. Preliminary observations for January through July 2026 suggest another record.

The ocean absorbs about 90% of the excess heat. Preliminary data through July put 2026 on course for a tenth consecutive year of record ocean heat content. Warmer water supplies energy to storms and expands as it warms, contributing to rising sea levels alongside melting land ice.

Global mean sea level reached its highest point in the satellite record, which began in 1993. Saulo says rising seas increase risks for 900 million people living along low coastal areas.

Water stored on land is also declining. In 2025, 42% of the assessed global area had below normal water storage, compared with a historical average of 25%. That is a gap of 17 percentage points, affecting the groundwater, soil moisture, rivers, reservoirs, glaciers and snow on which communities depend.

Warnings need resources behind them

The number of countries reporting warning systems covering multiple hazards rose from 56 in 2015 to 136 in 2025, an increase of 80 countries. Those systems can give governments and residents time to prepare for heat, floods and other threats.

Annie Wilkinson, a research fellow at the Institute of Development Studies, argues in her extreme heat analysis that people also need the ability to act on advice. An informal worker may lose essential income by stopping work, while staying indoors offers little protection if the home traps heat.

Wilkinson draws on the HeatNexus network and the If Cities Could Speak and Urban Futures research projects. Reflective roof paints can provide affordable protection in some communities, she writes, but the weakest roofs may be unsuitable even for that intervention.

Discussions at Bangkok's Global Heat Forum in October focused on warnings that explain likely effects on health in particular places. Wilkinson says effective protection requires coordination among weather agencies, health services, employers, housing authorities and social protection systems.

WHO identifies practical preparations: checking hospital water and electricity supplies, maintaining vaccine refrigeration, securing oxygen and medicines, planning referral routes and arranging mobile medical teams. Maternal care, immunisation, nutrition services, chronic disease treatment and mental health support all need to continue during weather emergencies.

The dates shaping the next response

WHO's September assessment and the WMO's November update describe a developing emergency, with the climate update using observations available through September. Governments face a preparation period before the expected El Niño peak and its strongest effects on annual global temperatures.

• April 2026: An estimated 146.5 million people in India were exposed to extreme heat.
• Late August 2026: A Himalayan glacier collapse and downstream flash floods devastated Nepal.
• September 5, 2026: WHO published its global public health situation analysis.
• November 9, 2026: The WMO released its climate update at COP31 in Antalya.
• November 2026 to January 2027: Pacific warming could approach four times the 0.5°C El Niño threshold.
• March 2027: The WMO plans to publish its final State of the Global Climate 2026 report.

UN Secretary-General António Guterres called for emissions cuts and support for countries facing the greatest exposure:

Leaders must get serious by cutting emissions faster, accelerating a just transition from fossil fuels and delivering the finance and protection vulnerable countries need,

For health authorities, the immediate tasks are concrete: keep clinics functioning, detect outbreaks early, protect drinking water and ensure that people receiving heat warnings have somewhere safe to go.

Key Points

• The WMO says WHO has classified anticipated El Niño health impacts as a health emergency for the first time.
• India faces overlapping risks from heat, dengue, leptospirosis, food insecurity and disrupted care.
• Global temperatures averaged about 1.47°C above the preindustrial baseline from January through September 2026.
• El Niño is expected to continue into early 2027, when its strongest effect on annual global temperatures is likely.
• WHO prioritises reliable hospital services, disease surveillance, safe water and support for vulnerable communities.
• The WMO's final climate report for 2026 is scheduled for March 2027.