The hydrography of Piura Department is determined mainly by the amount of rainfall originating in the Pacific Ocean. This rainfall is itself determined by the meeting of two ocean currents on the southern coast of the department, around the bay of Sechura: the cold Humboldt current at 13-19 °C, and the warm El Niño at 21-27 °C. These conditions lead to fluctuations in offshore sea temperatures, which are 18-23 °C in winter and spring, and 23-27 °C in summer and sometimes in autumn.