The Extent of El Niño and La Niña Influence on Australian Rainfall

Abstract El Niño‐Southern Oscillation (ENSO), where the central‐east tropical Pacific is unusually warm (El Niño) or cold (La Niña), is known to influence Australian rainfall. Here, we detail the extent of ENSO's influence on Australian monthly rainfall distributions and clarify its many complexities. We show La Niña to be a long‐lasting and wide‐spread intensifier of Australian rainfall throughout its lifecycle, particularly on extreme monthly rainfall. The reduction of rainfall during El Niño is comparatively limited; confined mainly to El Niño's developing phase and the southeast and northeast of Australia. A further complexity shows El Niño can intensify monthly rainfall during its mature phase. Within these broader impacts of ENSO are strong spatial and temporal differences, such that the expected rainfall impacts may not be consistently felt at the local‐scale. We propose methods to account for these complex climatic impacts at scales comparable to a river catchment scale.