The climate varies with terrain, from tropical along the coast to semiarid and hot in the north. Exceedingly hot and humid, the coastal belt includes some of the wettest places on earth. For example, Debundscha, at the base of Mt. Cameroon, has an average annual rainfall of 405 inches (10,287 mm).
The country has four patterns of drainage. In the south, the principal rivers flow southwestward or westward directly to the Gulf of Guinea — the Wouri, and lesser Dibamba, Bimbia and Mungo to the Cameroon estuary near Douala; Sanaga, Nyong, and Ntem further south along the coast; Akwayafe and Manyu (which joins Nigerian Cross), and the lesser Ndian and Meme in the north of coast.