Peru is traversed by the Andes, separating a narrow coastal region from the eastern tropical lowland. Peru has only one rainfall regime, with a dry and wet season, with the exception of the the Coastal Desert with negligible precipitation all year round. 

The effect of the Andes on the coastal region, together with the Humbolt current in the adjacent ocean is to keep the Pacific ITCZ to the north by reinforcing a very stable south Pacific anticyclone that produces subsidence all year long along the Peruvian and Northern Chilean coast. On the eastern side of the Andes, all year long rainfall is found in the lowland Amazon Basin, which is under the influence of the Atlantic trade winds, that bring moisture into region. Only during June-July do the winds and the rainfall recede. 
Along the Andes a summer rainfall regime is found, althugh the total annual ammounts do vary with location, more rainfall is found in the Central Andes than in the Northern and Southern Andes of Peru.
 
 
 

Region	Rainy season	Dry season
Coast	No rainy season	All year long
Andes	Aug-May	Jun-Jul
Northeastern Plains	Sep-Apr	May-Aug

 The climate of Peru can be subdivided into  4 regions

1)  Coastal district: Desert climate
      North: hot summers and warm winters.
       South: hot summers and mild winters.

2) Andes highlands: Tropical summer rain climate

3) Northeast and eastern slopes of the Andes: Tropical Rain climate
      low levels: permanently hot