During an El Niño event, Pacific surface currents shift into an unusual pattern. El Niño events occur when an unusual flow of warm water in the equatorial Pacific moves eastward to the coasts of Central and South America, suppressing the normal northward flow of the Peru Current. Pacific upwelling along the Peruvian coast ceases and a weak quatorial eastward current develops in response to a reduction in the strength of the trade winds. Global patterns of precipitation also change during El Niño events, bringing floods to some regions and droughts to others. In contrast to El Niño is La Niña, in which normal Peruvian coastal upwelling is enhanced, trade winds strengthen, and cool water is carried far westward in an equatorial plume.