El Ninos occur every two to seven years irregularly and tend to last for a single cycle. It is typical for these events to show signs of occurring during autumn, and then they strengthen over the winter and spring, with a drop off during the summer.
El Nino is a climate pattern that features the unusual occurrence of warming waters along the west coast of South America. It affects many different things including local weather, ocean currents and ocean temperatures. El Nino occurrences are indicated by the temperature of the surface of the sea rising for five three-month seasons. An El Nino occurs because equatorial westerly winds vanish and the Humboldt current gets weaker; this creates warmer conditions on the coast of South America.