Southeast Asian cities face increasing risks from urban heat island (UHI) effects driven by rapid urbanisation and climate change. With over 675 million people, urban populations are expected to grow by 60% by 2050. UHI intensifies health risks, especially for low-income groups and outdoor workers. However, decision makers still lack comparable regional evidence on how urban growth and climate change interact to shape UHI patterns. This project advances UHI research by expanding a validated assessment framework from Kuala Lumpur to the rapidly urbanising megacities of Hanoi and Jakarta. Building on the APN seed project CRRP2024-08SY-Wan, which demonstrated strong Local Climate Zone (LCZ)–Land Use/Land Cover (LULC)–temperature relationships, high-accuracy LCZ mapping, robust climate simulations, and stakeholder engagement, the project develops a harmonised multi-city framework for tropical Southeast Asia (SEA). The framework integrates long-term satellite observations, machine-learning LCZ-LULC classification, multi-source spatial datasets, high-resolution urban climate modelling and compound UHI–heatwave analysis under SSP2-4.5 and SSP5-8.5. This standardised approach enables cross-city comparison of urban heat drivers, climate risks and adaptation pathways, generating transferable evidence for tropical megacities. The
project will strengthen evidence-based urban planning, support climate-resilient policy development and enhance regional scientific collaboration across SEA.