The 1st Global Forum on Heat and Health (Hong Kong, China, 17-20 December 2018) brought together over 150 interdisciplinary experts and practitioners from 33 countries. The Forum formally launched the Global Heat Health Information Network (GHHIN) – its parent inter-agency coordination body and governance mechanism – and informed a global common action agenda for heat risk management to human health. This summary report covers the call to action, action agenda, and contents of the Forum broken down by GHHIN organizational pillar.