The Pendjari River has an impressive gallery forest. The park includes both Sudan and Northern Guinea savannas, with areas of grassland dominated by Acacia sieberiana and Mitragyna inermis or Terminalia macroptera. There is a high annual rainfall of around 1,100 millimetres (43 inches); The park is open year-round, although from June–November rainfall can be heavy and certain parts of the park may be inaccessible.