The impacts of climate change on agriculture are governed by erratic precipitation and water demand that contribute to a decline in crop yield. Designing irrigation schedules that increase crop yield while conserving water is an urgent need of the hour. For this, controlled crop experiments were conducted during the 2021–2022 season on wheat crops in the semi-arid region of western Uttar Pradesh to understand the dynamic interaction between environment, soil, and plant parameters. Using these parameters, a plant-based index known as the crop water stress index (CWSI) is studied under two different environmental conditions. CWSI is empirically derived using three parameters: air temperature (Ta), canopy temperature (Tc), and vapor pressure deficit (VPD). The two different environmental conditions were created for plots 1 and 2, subjected to a similar type of drip irrigation treatment with a 50% maximum allowable depletion (MAD). Plot 1 was roof covered by polyethylene sheet that blocked around 50% of incoming solar radiation and plot 2 was open to the sky. The weather variables of Ta, VPD, and wind speed decreased by 5%, 21%, and 44%, respectively, owing to the presence of the partial shade condition of the polyethylene sheet. The non-stressed condition of the lower baseline was designed for open sky conditions with the help of an additional drip irrigated plot 3, subjected to a 25% MAD. The lower baselines for the pre-heading and post-heading stages of wheat growth were (Tc − Ta)LL = − 1.39 (VPD) − 0.66 and (Tc − Ta)LL = − 1.29 (VPD) − 2.19, respectively. Using the lower baseline devised from plot 3 as a reference scenario for non-water stressed conditions, empirical CWSI values for both open-to-sky and partially shaded conditions were calculated. It was seen that the mean CWSI values of plot 1 and plot 2 were 0.25 and 0.1, respectively, which implies a 60% decrease in water stress in plot 2. The crop yields of plot 1 and plot 2 were 3684 kg/ha and 5011 kg/ha, respectively. The lesser crop water demand within the polyethylene sheet leads to a 107% water savings than the open sky conditions. This study quantifies the significance of well-lit, sunny conditions for the development of CWSI and also signifies the cumulative effect of weather variables on water management and crop yield.