Abstract: Urbanization and changes in land use significantly impact vegetation patterns, land surface temperature (LST), and urban heat island (UHI) effects. This study uses multi-temporal satellite images from 2000 to 2025 to examine seasonal and long-term land use and land cover (LULC) changes in Dhaka and Chittagong, Bangladesh. It also looks at derived indices such as NDVI, LST, UHI, and UTFVI profiles. The findings show considerable urban growth over the 25-year period. In Chittagong, built-up areas grew by 47.82% to 53.88% across different seasons, leading to a marked reduction in agricultural land and barren fields. Dhaka showed an even more aggressive trend, with built-up areas nearly doubling by taking over croplands and wetlands. NDVI metrics reveal increased spatial fragmentation and serious vegetation loss within urban centers, even though there was some localized recovery during the monsoon. Thermal assessments indicate a steady rise in LST. From 2000 to 2025, peak monsoon LST increased from 36.06°C to 39.81°C in Chittagong and from 32.61°C to 39.56°C in Dhaka. At the same time, maximum UHI intensities grew, reaching 3.51°C in Chittagong and about 3.0°C in Dhaka, mainly during the monsoon. Overall, these results establish a strong link between rapid urban expansion and increased thermal stress on microclimates, providing important insights for climate-resilient urban planning in Bangladesh.