Objective Rapid urbanization has significantly exacerbated the deterioration of the urban thermal environment. A deep understanding of the influence mechanism of urban form is thus crucial for guiding urban planning and mitigating urban heat stress.

Method This study focuses on a typical high-density region, the central urban area of Shanghai. Multi-source data—including road networks, land use, building data, remote sensing imagery, and POIs—were integrated to quantify urban morphology and land surface temperature (LST) at the block scale from the perspective of functional zones. Using Random Forest regression (RFR) and Partial Dependence Plot (PDP) analysis, the study systematically elucidated the relative contributions and nonlinear influences of urban morphological factors on LST across various functional zones.

Result The findings demonstrated significant seasonal differentiation and spatial heterogeneity.The regulatory role of two-dimensional landscape indicators was prominent in spring and summer, with notable cooling effects in green spaces, squares, and transportation zones. In autumn and winter, three-dimensional building morphology became the dominant factor, particularly within commercial, industrial, and residential areas.The mechanisms underlying temperature increases and decreases also varied across different seasons and functional zones.During spring and summer, cooling in green spaces and squares was primarily achieved through percentage of water (PW) and sky view factor (SVF),where as transportation zones relied more on patch density (PD) and percentage of green (PG). In autumn and winter, average building height (AH) and architecture height standard deviation (AHSD) emerged as the dominant cooling factors.

Conclusion By integrating functional zones with RFR and PDP analysis, this study identifies key thermal environment drivers in heterogeneous regions and elucidates their nonlinear relationships with LST.These findings advance our understanding of the seasonal dynamics of urban thermal environments and provide a scientific basis for formulating differentiated urban form regulation strategies.