Parana River Basin Rainfall for April 1985 - 1999

Clear zonation can be seen with the north eastern area receiving the highest rainfall. This area of southern Brazil is classes as tropics and moist tropical air is the common feature as the river travels southwards it enters the subtropics and a more temperate climate prevails. The western reaches of the basin receives the least rain fall mainly due to the influence of the mountain range of the Andes.

The terrain in the upper basin is steep which promotes runoff while the mid and lower sections are very flat and are subject to extensive flooding