The aim of this study is to elucidate the primary factors influencing the development, strength, and longevity of Mesoscale Convective Systems (MCSs) in southwest Iran. Focusing on dynamic and thermodynamic factors, this research investigates their impact on MCSs' maximum area, longevity, and precipitation characteristics. The study reveals that MCS characteristics are intricately linked to environmental factors such as humidity, Convective Available Potential Energy (CAPE), and low-level wind shear, predominantly within the Red Sea convergence zone. These factors are, in turn, influenced by larger atmospheric phenomena like Sudan's low, Saudi Arabia's high, and the Azores high. Multiple linear regression analysis identifies low-level wind shear along the Red Sea convergence zone and the 300hPa wind speed along the subtropical Jetstream as significant predictors for both the maximum and mean precipitation of MCSs. Notably, CAPE over the west of the Red Sea emerges as crucial for maximum precipitation, while sensible heat flux over Eastern Europe is key for mean precipitation estimation. The findings also underscore that humidity variables and 850hPa wind speed are vital in determining the longevity and area of MCSs. This study contributes to a better understanding of the environmental conditions influencing MCS occurrence, aiding in the prediction of heavy precipitation events in subtropical regions like southwest Iran.