Principles of equitable and reasonable use underpin international water agreements. Despite the potential for hydrologic information to enhance resilience to extreme events, comparable application of just principles to the distribution of hydrometeorological data is poorly established. Within the Ganges–Brahmaputra–Meghna (GBM) river basin, we find that water allocation agreements are codified into treaties or Memorandums of Understanding (MoUs). Analogous decisions regarding hydrometeorological data sharing are often internalized at the level of river basin organizations and are not upheld as MoUs. This institutional structure provides extremely limited data to the most downstream nation of Bangladesh. Available precipitation and discharge stations are well below the minimum densities recommended by the World Meteorological Organization. Forecasters in Bangladesh therefore contend with vast areas of geopolitically ungauged catchment, precluding the application of basin-wide modelling approaches driven by observed data. Thus, capacity for increasing resilience to extreme events within Bangladesh is obstructed, demonstrating the potential for perceived injustice related to distribution of hydrometeorological data. Consensus that water is a human right warrants the application of equity to water allocation. But is security from water-related disasters also a human right? As hydrometeorological data can be a powerful resource with potential to profoundly affect lives and livelihoods, enhanced awareness of justice related to data sharing is needed.