This work provides forecasts of water supply for the semi-arid Elqui River Valley, Chile, at periods prior to the October–January growing season. Forecasts are constructed provide water rights holders, whose allocations are subject to annual change, with an advanced indication of expected allocations. Forecasts, based on global and local indicators, are best suited to provide an initial indication of allocation category (above, near, or below normal) in May and are quantified in September.