At the end of September, storage levels by river basin were higher than the September storage averages (1990/91 to 2023/24), except for the Ave, Mondego, Mira, and Ribeiras do Algarve basins.

Of the 60 monitored reservoirs, 10 have water availability levels exceeding 80% of their total volume and five have water availability levels below 40% of their total volume, according to SNIRH data.

The Guadiana and Cávado basins had the highest water volume, at 82% and 75.5%, respectively, followed by the Douro (74%), Tejo (72.6%), Arade (72.7%), Oeste (72.4%), and Lima (58.2%).

At the end of September, the Barlavento basin had the lowest water volume, at 45.3%, followed by the Sado (46.8%), Ave (48.3%), Mira (53.4%), and Mondego (57%).

Each river basin may have more than one reservoir.

According to the Portuguese Institute of the Sea and Atmosphere (IPMA), total precipitation in September was below normal, corresponding to approximately 60% of the average value for the 1991-2020 reference period.