Turning weather and climate data into early health action

Early warning is most effective when governance, data, and protocols align, helping health systems act earlier on climate-sensitive risks.

Introduction

The Greater Mekong Subregion (GMS)—spanning Cambodia, the Lao People's Democratic Republic (PDR), Thailand, Viet Nam, and areas in the southern part of the People’s Republic of China—is highly exposed to climate-sensitive health risks. Its tropical climate and ecology already create favourable conditions for vector-borne diseases, such as dengue and malaria, while floods, heat, and water insecurity continue to affect public health outcomes across the region .

Climate change is compounding these pressures by expanding mosquito habitats, lengthening transmission seasons, and increasing the likelihood of outbreaks and other infectious disease risks . At the same time, more intense floods and heat extremes are straining sanitation, infrastructure, and health services, especially for poorer and more exposed groups.

In this context, climate-informed early warning can help shift public health action from reactive outbreak response to anticipatory preparedness. By combining climate and environmental information with routine surveillance, early warning systems can identify periods of elevated disease risk early enough for health authorities to act before cases surge. However, skilful prediction alone will not protect communities. The real test is whether warnings and surveillance triggers lead to timely decisions and practical action, making this issue directly relevant to Sustainable Development Goals 3 (Good Health and Well-Being), 13 (Climate Action), and 16 (Peace, Justice and Strong Institutions).

Analysis

Climate-informed early warning is becoming more feasible.

The case for climate-informed early warning in health is well established. Dengue transmission is shaped by climatic conditions , especially rainfall and temperature, and these relationships can provide lead time for public health action. Across the GMS, governments and partners are increasingly using seasonal outlooks, environmental indicators, and routine surveillance data to identify periods of elevated risk before health systems come under acute strain. This reflects a broader shift from reactive toward anticipatory action .

Cambodia and the Lao People’s Democratic Republic (Lao PDR) illustrate this transition. Both countries are strengthening broader multi-hazard early warning systems and exploring how health can better integrate into national warning frameworks . In the Lao PDR, climate information is being linked with District Health Information Software 2 (DHIS2)-based health reporting to support dengue forecasting and related risk analysis. Cambodia has strengthened epidemic surveillance and is using forecasting approaches to support dengue preparedness and climate-resilient health planning . These developments show that the technical foundations for anticipatory action are increasingly in place.

The real gap is between warning and action.

This distinction reflects the standard early warning system value chain: risk knowledge (the foundation), monitoring and forecasting (the detection), dissemination and communication (the warning), and preparedness and response (the action) . Forecasting risk is part of the chain, but early warning only becomes useful when information moves through the full sequence and leads to action. Evidence from the broader dengue literature supports this point: the World Health Organization's Early Warning and Response System is most effective when warnings trigger timely and sufficiently strong measures; where response is weak or delayed, the value of the warning sharply reduces. For this reason, effective early warning systems for health depend on seven operational ingredients.

Early warning is ultimately an institutional capability.

Taken together, these seven elements point to a broader lesson: the challenge in early warning for health is not prediction alone but the systems needed to act on it. Models, surveillance, and digital tools all matter, but their value ultimately depends on whether institutions can turn foresight into timely, authorized, and properly resourced action. Climate-informed early warning can help health systems prepare for increased demand, protect routine services, and reduce peak pressure during outbreaks or climate-related events. Dengue provides a practical starting point for building the warning-to-action systems that health services will increasingly need as climate risks grow.

Implications

The opportunity is to support better forecasting and help countries translate technical progress into systems that are practical, scalable, and embedded in routine public health decision-making. Investments in climate data, surveillance, modeling, and digital platforms are already creating a stronger foundation for anticipatory action. The next step is to reinforce institutional arrangements that allow these tools to deliver value in practice, including coordination across sectors, trigger-based protocols, communication pathways, financing for early action, and workforce capability. To be effective over time, climate-informed health early warning needs to be embedded in routine sector planning, with clear mandates, recurrent resourcing, and arrangements for ongoing operation and maintenance.

Development partners can make a particularly strong contribution by

• helping connect health, meteorological, and disaster management institutions;
• improving data-sharing and interoperability;
• strengthening warning-to-action protocols; and
• building capacity at subnational levels, where many early decisions are implemented.

In practical terms, this means supporting joint meteorological-health working arrangements, trigger-action standard operating procedures, escalation pathways, and budget mechanisms that allow early action to be activated before impacts escalate.

There is clear scope to facilitate regional learning across the Greater Mekong Subregion, where shared climate patterns, dengue risk, and common implementation challenges create a strong basis for exchanging experience and adapting good practice.

Early warning for health is a practical entry point for strengthening climate-resilient health systems and improving how institutions manage risk under changing climatic conditions. This supports SDG 3 by strengthening preparedness and protecting service continuity, SDG 13 by enabling earlier adaptation, and SDG 16 by improving coordination and institutional responsiveness.

Note: This Insight is part of regional technical assistance on Health Cooperation in the Greater Mekong Subregion , the team appreciates review comments from Anna C. Orquiza, ADB Disaster Risk Management team, Climate Change and Sustainable Development Department.