This study evaluated a comprehensive plant water stress index that integrates the canopy temperature and the environmental conditions that can assist in irrigation management. This index—Comprehensive Stress Index (CSI)—is based on the reformulation of the leaf energy balance equation. Specifically, CSI is the ratio of the temperature difference between a dry leaf (i.e. a leaf with a broken stem) and a live leaf (on the same tree) [i.e. Tdry-Tleaf] and the difference between the vapor pressure inside the stomatal cavity at saturation and the vapor pressure of the air at ambient temperature [i.e. es(TL)-e(TA)]. The required measurements to compute CSI include dry leaf temperature, live leaf temperature, relative humidity, and air temperature at the tree being monitored. In this study, all measurements were obtained using a single sensor suite per tree connected to a wireless mesh network. The sensor suite included two thermal infrared sensors, one for the dry leaf and one for the live leaf, both of which were housed in the same unit with approximately the same environmental conditions. The CSI is a dynamic index with a value for every data sample collected. For a single index representing each day, the CSI was manipulated in two ways. First, the CSI was integrated with respect to time from 10 AM to 6 PM to obtain the Integrated Comprehensive Stress Index (ICSI). Second, the CSI was averaged from 1 PM to 3 PM to obtain the Average Comprehensive Stress Index (ACSI). Both ICSI and ACSI were compared to other stress indices, including CWSI and IDANS. Results indicate that ICSI and ACSI are satisfactorily correlated with midday stem water potential (SWP). The ICSI and ACSI indices may be more convenient than other stress indices because they require measurements only at the tree being monitored.