Water is getting increasingly scarce & expensive commodity in most parts of the world. This is especially true for irrigation systems, where effective and responsible water management is indispensable. For effective operation of irrigation systems, an estimate of irrigation water requirement (IWR) is of basic concern. Since IWR is influenced by rainfall & evapotranspiration (ET), a reliable estimate of expected rainfall and ET is of great importance. Efficient utilization of rainfall during rainy season will help in saving irrigation water in the storage reservoirs that could be used in the dry season. The present work was aimed at developing computer software for reliable rainfall and ET estimates. The software are designed for a broad range of users, from field engineers and extension specialists to water managers at the farm, district, and higher levels. These software can play an important role in rainfall prediction and ET estimates for use in irrigation planning and scheduling, water resources management, environmental assessment and other hydrological studies focusing on enhanced water use efficiencies of irrigation projects.