Urbanization　intensifies　urban　heat　and　compromises　thermal　comfort.　However,　few　studies　have　examined　the　interactions　of　Urban　Heat　Island　(UHI)　between　neighboring　cities　and　the　impacts　of　expanding　satellite　towns　on　central　urban　areas　(CUA).　We　conducted　a　series　of　WRF/BEP-BEM　simulations　during　a　summer　heat　wave　in　Fuzhou,　China,　to　understand　how　extensive　urbanization　and　complex　topography　affect　thermal　comfort.　Control　runs　reveal　an　intense　UHI　centered　on　Fuzhou＇s　CUA.　Comparisons　with　scenarios　where　urban　land　use　and　terrain　are　altered　demonstrate　that　urbanization　degrades　thermal　comfort　citywide　by　elevating　heat　stress　while　valley　-basin　topography　worsens　midday　heat　but　alleviates　nighttime　humidity.　The　urban　heat　island　circulation　above　the　CUA　suppresses　the　valley　wind　circulation　and　prevents　the　sea　breeze　front　from　advancing　inland　in　the　afternoon.　Notably,　CUA　urbanization　enhances　sea　breezes　in　a　satellite　town,　inducing　afternoon　＂cool　islands＂.　Interactions　between　CUA　and　satellite　towns　appear　minimized,　with　urbanization　impacts　confined　locally.　Future　expansion　according　to　the　＂Fuzhou　2035＂　Master　Plan　shows　negligible　effects　on　thermal　comfort　in　CUA.　Our　findings　enhance　understanding　of　intra-urban　UHI　dynamics　in　complex　terrains.　The　outcomes　directly　inform　urban　planning　and　climate　adaptation　strategies　to　promote　Fuzhou＇s　livability　and　resilience.