A healthy cities agenda for extreme heat adaptation in urban settings.

Extreme heat has become a predictable urban health emergency. Here, we synthesize evidence from 2024 and 2025 from peer-reviewed studies, multilateral agency reports and city heat-action plans on urban heat adaptation and health. Based on this evidence, we propose a city-level agenda grounded in the World Health Organization Healthy Cities framework. We outline interventions with demonstrated benefits, including urban greening and blue infrastructure (such as rivers, canals, wetlands and other urban water features that reduce ambient temperatures), cool roofs and reflective pavements, shaded pedestrian and transit corridors, as well as housing retrofits that prioritize passive cooling and equitable access to efficient cooling. We place equal emphasis on health-system readiness: impact-based early warning, surge protocols, clinician training, cooling centres and strengthened surveillance. We examine implementation challenges in financing, governance, equity, technical capacity and regulation, and propose practical city governance responses. We emphasize two contributions to urban heat adaptation policy and practice: hyperlocal targeting tools to maximize equity and effectiveness, and positioning health systems alongside infrastructure, rather than treating adaptation as a purely built-environment intervention.