The river flows in a northwesterly direction for approximately 150 km (93 mi) through a fertile valley that is a major agricultural region for northern Peru.

Historically, the Piura River's primary mouth was further north but severe El Niño events in recent decades has diverted much of its flow to the south.

[2] The Piura River is susceptible to major flooding as its location is near the fluctuating southern boundary of the Intertropical Convergence Zone.

In most years, the ITCZ lies to the north of coastal Peru leading to very arid desert conditions in the lower Piura River basin.

During El Niño events, however, the ITCZ will shift further south bringing monsoon-like rains to the desert region.