<p>The current climate change poses a significant threat to the safety of dam spillways against the rock scour due to increased precipitation. The plucking of rock blocks is the dominating mechanism in this scouring process, which is influenced by various hydraulic and geomechanical factors at the spillway site. This article studies the impact of specific parameters—flow rate, joint opening and block protrusion on the hydraulic pressure, using a pilot plant scale spillway model. The model test results reveal that the hydraulic pressure fluctuations on the top of the instrumented block, i.e., on the spillway surface, govern the uplift process as the pressure fluctuations within the joint remain similar across varying test conditions. A mathematical model is developed to predict the extreme pressure fluctuations that represent the critical conditions for block uplift. This model enables the end user to readily estimate the critical hydraulic pressure on the spillway surface to assess the vulnerability of spillway structures, contributing to improved resilience and disaster risk reduction in the context of a changing climate. Remarkably, the margin of error (<i>RMSE</i>) between most of the measured and modeled extreme pressure fluctuations is found to be between 0.04 to 0.37, well within acceptable limits. Also, the normalized <i>RMSE</i> (<i>NRMSE</i>) values, normalized with difference between maximum and minimum pressure values of the measured data, are lying 18 to 35% which defines a moderate fitting of the pressure data.</p>