Extreme heat is a growing global health threat, yet reliable and policy-ready data remain scarce. To address this gap, and aligned to the UN Secretary-General’s Call to Action on Extreme Heat, WMO is producing the first global scientific synthesis report focused on the health impacts of extreme heat. Coordinated by the University of Washington and developed with over 40 international experts through the Global Heat Health Information Network, this report will consolidate the best available science to answer key policy questions and support evidence-based decisions to reduce extreme heat risks worldwide. The planned publication date is November 2026.