This study assesses the relationship between global sea surface temperature (SST) and a regional index of rainfall (NWPR) in Piura-
Tumbes, a coastal region in northwestern Peru, over the period 1965–2008 by means of the Pearson product-moment correlation.
The results show that this area is strongly influenced by three indices: El Ni˜no-Southern Oscillation (ENSO) Ni˜no3.4 region, the
Indian Ocean Dipole (IOD), and the equatorial Atlantic Oscillation (ATL3). In particular, a positive correlation has been found
with the two first indices (Ni˜no3.4 and IOD) and a negative one with ATL3 with several months of delay.This allows developing a
forecast regression model for monthly rainfall inNWPeru withmonths in advance.The results show that linear regression model is
not enough to provide satisfactory results; however, a nonlinear regression model improves considerably the prediction of rainfall
anomalies in NWPeru.