Background: The leaf temperature (TLEAF) is one of the most important physical parameters governing water and carbon flux, including evapotranspiration, photosynthesis and respiration. Cnidium officinale is one of the important folk medicines for counteracting a variety of diseases, and is particularly used as a traditional medicinal crop in the treatment of female genital inflammatory diseases. In this study, we developed a model to estimate TLeaf of Cnidium officinale Makino based on black globe temperature (TBGT). Methods and Results: This study was performed from April to July 2018 in field characterized by a valley and alluvial fan topography. Databases of TLEAF were curated by infrared thermometry, along with meteorological instruments, including a thermometer, a pyranometer, and an anemometer. Linear regression analysis and Student’s t-test were performed to evaluate the performance of the model and significance of the parameters. The correlation coefficient between observed TLEAF and calculated TBGT obtained using an equation, developed to predict TLEAF based on TBGT was very high (r2 = 0.9500, p < 0.0001). There was a positive relationship between TBGT and solar radiation (r2 = 0.8556, p < 0.0001), but a negative relationship between TBGT and wind speed (r2 = 0.9707, p < 0.0001). These results imply that heat exchange in leaves seems to be mainly controlled by solar radiation and wind speed. The correlation coefficient between actual and estimated TBGT was 0.9710 (p < 0.0001). Conclusions: The developed model can be used to accurately estimate the TLeaf of Cnidium officinale Makino and has the potential to become a practical alternative to assessing cold and heat stress.