An El Niño state occurs when the central and eastern equatorial Pacific sea-surface temperatures (SSTs) are substantially higher than usual. The National Oceanic and Atmospheric Administration (NOAA) defines an El Niño event when the NIÑO 3.4 area has sea-surface temperatures at least 0.5 ºC higher than normal for five consecutive three-month-averaged periods. During the last 25 years, Somalia has been affected by six moderate-to-strong El Niño events: 1991-2, 1994-5, 1997-8, 2002-3, 2006-7, and 2009-10 in which floods of different magnitudes were reported. The 1997/98 was the strongest followed by that of 2006.