The knowledge of Quantitative Precipitation Forecasts (QPFs) for the following weeks combined with the updating of hydrological conditions of the system is fundamental for water distribution management and irrigation purposes. This developed tool for irrigation management has a higher reliability in comparison with flood forecasting systems, because it is characterized by slower and persistent weather dynamics over larger areas. One can consider, for instance, the large difference in hydrological processes between rainfall events with intensities that can reach up to 100 mm/h over areas of a few tens of km2 (flood events) and events with evapotranspiration rates of about 8-9 mm per day over areas of a few thousand of km2 (drought events). Obtained results show, in fact, how the proposed drought forecasting system is able to have a high reliability up to 15 days as lead time at least.