Urban Impacts on Precipitation in the Greater Ho Chi Minh City Metropolitan Area, Vietnam

Urban impacts on precipitation have been extensively studied in mid‐latitude developed countries. However, despite the recent rapid urban development, such studies focusing on Southeast Asian cities remain limited. This study evaluated urban impacts on precipitation in the Greater Ho Chi Minh City Metropolitan area (GHCM) by multi‐case numerical simulations using the Weather Research and Forecasting model (WRF) for 217 precipitation events during the rainy seasons from 2013 to 2022. We conducted each simulation with and without 2020 urban land use (URB and NO_URB), and under two different initial and boundary conditions to enhance the robustness of the results. Results show that daily precipitation over the central urban area was up to 30% greater in URB than in NO_URB, with statistical significance ( p < 0.05), especially between 15:00 and 22:00 LT. URB also exhibited higher sensible heat flux (+250 W m −2 ), higher convective boundary layer height (+350 m), and lower surface pressure (−0.2 hPa) than NO_URB at 14:00 LT. These thermodynamic changes caused greater Convective Available Potential Energy and smaller Convective Inhibition than those of NO_URB, indicating intensified atmospheric instability due to urbanization. In addition, grid‐scale horizontal water vapor convergence was stronger in URB than in NO_URB. This convergence is caused by the lower surface pressure in URB than NO_URB. As a result, water vapor accumulated within the convective boundary layer. These results indicate that the urban area strengthened atmospheric instability and grid‐scale horizontal water vapor convergence, resulting in greater precipitation than the non‐urban case.