El Niño in the Americas, 2026–2027: public health risks and preparedness priorities

8 JULY 2026, WASHINGTON, D.C.—

El Niño conditions forecast for 2026–2027 signal overlapping public health and humanitarian risks across the Americas. Exceptionally warm global ocean and atmospheric temperatures may amplify or modify expected climatic anomalies, including droughts and floods, and their associated public health impacts. Although the intensity and geographic distribution of these impacts remain uncertain, historical patterns and current forecasts indicate increased risks of both drought-related and flood-related emergencies, which should be closely monitored to anticipate and mitigate emerging public health threats.

These risks may be compounded in countries and territories with pre-existing vulnerabilities, including food insecurity, limited access to safe water, migration, displacement, poverty, recurrent outbreaks, and constrained health services.

RISK OUTLOOK AND IMPLICATIONS

Priority areas for the El Niño event fall into two broad risk patterns (Figures 1 and 2). First, in Central America, the Caribbean, northern South America, and the Amazon Basin, drier and hotter conditions may increase the risk of drought, water scarcity, food insecurity, wildfires, heat stress, respiratory illness, and arboviral disease transmission. Second, in parts of Ecuador, northern Peru, western Colombia, southern Brazil, Paraguay, Argentina, and the southern United States, wetter conditions may increase the risk of flooding, landslides, displacement, infrastructure damage, and outbreaks of waterborne and vector-bornediseases. Because El Niño impacts unfold over a period of 1–2 years, these priority areas require sustained monitoring, particularly during the year following El Niño onset, when the most significant health impacts have historically been observed. Health risk levels may shift by region, by country, within countries, and between time periods.

FIGURE 1. Anticipated El Niño impacts in Latin America and the Caribbean in 2026.

Source: Map excerpt adapted from United Nations Office for the Coordination of Humanitarian Affairs (OCHA). Latin America & Caribbean: El Niño Humanitarian Snapshot (April 2026). Geneva: OCHA; 2026. Available from: https://reliefweb.int/report/guatemala/latin-america-caribbean-el-nino-humanitarian-snapshot-april-2026

FIGURE 2. Probabilistic forecasts of surface air temperature for the season June–August 2026.

Source: World Meteorological Organization (WMO). Global seasonal climate update for June–July–August 2026. Geneva: WMO; 2026. Available from: https://wmo.int/media/update/global-seasonal-climate-updatejune-july-august-2026

Public health implications are expected to follow different pathways under dry and wet conditions. Drier conditions may deepen food insecurity and malnutrition, reduce water availability, increase household unsafe water storage and Aedes breeding sites, intensify heat stress, and increase exposure to wildfire smoke and associated respiratory illnesses. Extreme weather conditions may damage water and sanitation infrastructure, contaminate water sources, increase flooding and displacement, and create conditions favorable for vector-borne diseases, cholera, and other waterborne diseases. These climate-related pressures may also disrupt routine immunization, surveillance, cold chain supply, outreach services, maternal and child health services, and access to care, particularly in the context of existing regional immunity gaps and the ongoing measles transmission risk.

PUBLIC HEALTH RECOMMENDATIONS

PAHO Member States should strengthen climate-informed surveillance and early detection, by linking meteorological, environmental, epidemiological, entomological, and health service data to support timely epidemic intelligence for enhanced early warning and anticipatory action. Surveillance should prioritize the main health risks associated with El Niño, including arboviral diseases; malaria; cholera and other waterborne diseases; measles and other vaccine-preventable diseases; respiratory illness; heat-related illness; malnutrition; and events linked to flooding, drought, wildfires, and displacement.

Preparedness should be guided by expected local impacts, including drought, flooding, heatwaves, wildfires, storms, displacement, disruption of services, and increased demand for care. Health authorities should review contingency plans; ensure continuity of essential health services; strengthen water, sanitation, and hygiene (WASH) preparedness; conduct water-quality monitoring and emergency water treatment; reinforce vector surveillance and control; highlight community engagement; protect vulnerable populations; and maintain risk communication tailored to expected local impacts.

For arboviral diseases, preparedness actions should prioritize integrated Aedes surveillance and control in areas affected by water scarcity, intermittent water supply, flooding, and population displacement. These actions should include intensified monitoring of entomological and epidemiological indicators; identification and targeting of high-risk localities; actions to reduce unsafe household water storage and other productive breeding sites; and maintenance of vector-control operations during climate-related disruptions. Countries should also review readiness for early detection and clinical management of dengue and chikungunya, including mechanisms for monitoring severe cases and deaths.

Monitoring should distinguish between climate conditions and public health impacts. Climate monitoring should track the evolution and possible strengthening of El Niño conditions, alongside subnational drought and rainfall anomalies, heatwave alerts, wildfire activity and air quality. Public health monitoring should follow water shortages, food security deterioration, displacement, and health service disruptions; increases in dengue and other arboviral diseases, including the emergence of transmission and reported cases in areas with no previous history of arboviral transmission, as well as trends in severe cases, hospitalizations, and deaths; malaria trends in endemic and receptive areas; cholera or diarrheal disease signals; measles transmission; and impacts on maternal and child health.

Key takeaways:

• Oceanic and atmospheric conditions indicate a rapid transition to El Niño in the equatorial Pacific, with forecasts suggesting a high probability of development during 2026 and persistence into early 2027. As of June 2026, forecasts indicate an 82% probability of El Niño developing during May–July 2026 and a 96% probability of persistence through the Northern Hemisphere winter of 2026–2027.

• The outlook points to uneven public health risks across the region. Above-normal temperatures are forecast across much of the Americas, while rainfall anomalies may include drought in parts of Central America, the Caribbean, northern South America, and the Amazon Basin, and increased rainfall along parts of the Pacific coast of South America and the Southern Cone.

• The convergence of climate-sensitive health risks with priority public health risks is concerning. These include malnutrition, cholera and other waterborne diseases, dengue and other arboviral diseases, measles and other vaccine-preventable diseases, malaria, respiratory illness, heat stress, maternal and child health impacts, mental health and psychosocial needs, gender-based violence, injuries, and envenoming.

• Preparedness should translate seasonal forecasts into operational readiness. Priority actions include climate-informed surveillance, early warning, risk communication, continuity of essential health services, WASH preparedness, vector surveillance and control, nutrition support, heatwave readiness, and wildfire/smoke exposure preparedness.

• The risk of chikungunya resurgence should also be considered, particularly in countries with prolonged periods of limited transmission and potentially increased population susceptibility, where climate anomalies may compound existing epidemiological vulnerability.

Funding Statement

PAHO.

Data Availability Statement.

Data are available from Public Health Situation Analysis: El Niño in the Americas, 2026–2027.