Ilocos Sur is bounded on the north by the provinces of Ilocos Norte and Abra, and on the south by La Union. The Cordilleran provinces of Benguet and Mountain Province rise to the east while the blue depths of the South China Sea lie to the west. Except for the coastal plains, much of the land is rugged. Ilocos Sur experiences the dry season from November to April while the rest of the year is mostly wet. Monsoons and storms that blow in from the China Sea affect the province.