The Victorian government spends tens of thousands of dollars artificially opening Intermittently Open/Closed Estuaries that become closed to the ocean. IOCE close when onshore deposition exceeds the capacity of the ebb-tidal prism to remove sediment from the entrance channel. Entrance closures often persist for months to years and can present a range of challenges for management. Despite providing short-term flooding relief, artificial openings do not always persist for more than a day or two as large quantities of sediment are redistributed landward. Infill of the channel commences after removal of the hydraulic head between the estuary and the ocean following lagoon drainage. The opening duration is then a function of the subsequent geomorphic conditions. This study uses historical records of entrance state and marine and fluvial conditions to develop a method of predicting the opening duration. Multiple linear regression models are developed from historic data and a Monte Carlo simulation is used to populate each model. The outcome is a predictive tool that managers can use to input both the current and forecast conditions to determine the probable entrance opening duration. This method will form a decision support tool for estuary entrance management that will have the capacity to learn and improve in future. It can also provide a complimentary module to work alongside existing entrance management strategies.