El Nino

Southern Oscillation warming and cooling episodes on a very large scale, that appear cyclical (every 3 - 7 years). Warm water pools in the east closer to the Americas during El Nino conditions resulting in a shift in weather patterns across the Pacific. In Australia (particularly eastern Australia), El Nino events are associated with an increased probability of drier conditions.

The converse occurs during La Nina conditions with cooling of the central and eastern Pacific Ocean, resuling in a higher probability of rain in Eastern Australia. Also increased convection or cloudiness over tropical North Australia, Papua New-Guinea, and Indonesia