El Nino is one extreme of the El Nino-Southern Oscillation (ENSO) phenomena, in which La Nina is its counterpart. El Nino (the warm phase) occurs when warmer than average sea surface temperatures (SSTs) prevail over the central and eastern equatorial Pacific Ocean (from late winter to late autumn), accompanied by high atmospheric pressure over the western Pacific. This high atmospheric pressure typically leads to lower than average rainfall over Australia during El Nino years. La Nina (cool phase) on the other hand, occurs when cooler than average SSTs prevail over the central and eastern equatorial Pacific. This is accompanied by a low atmospheric pressure over the western Pacific, thus typically bringing above average rainfall to mainland Australia during La Nina years. Two back-to-back La Ninas, brought Australia's wettest two year period on record (2010-2011) leading to unprecedented flooding across the eastern states. The last strongest classical El Nino occurred in 2002-2003 with 2009-2010 being a weak El Nino. Over the past few months there has been a noticeable warming of the eastern and central Pacific with increasing odds towards an El Nino developing later this year. The bad news is that El Nino years are associated with below average rainfall, mainly across the northern and eastern parts of Australia. Due to the lack of cloud cover, El Nino years also tend to bring above average temperatures as the sun has plenty of time to heat the surface. This comes after Australia's hottest year in 2013, a year in which many hot records were broken, records that were not driven by ENSO but as a consequence of the global warming observed across the globe throughout the 20th century and early 21st century.