The occurrence of climate variations known as ENSO phases are caused by anomalies in ocean surface temperature in the so-called Niño 3.4 region in the Central Equatorial Pacific. These anomalies are officially used by NOAA (U.S. National Oceanic and Atmospheric Administration) to define whether there is a probability of occurrence of a La Niña, El Niño or neutral phase with global impact. In Uruguay, South America, the impact of climatic variations associated with ENSO phases on agricultural and pasture production is well known.