A negative IOD often results in more rainfall than average over southeastern Australia. The map below shows rainfall during negative IOD years is generally above average (decile 8 or higher, indicated by the blue shading) across the mainland's southeast. In no part of the country is there a tendency towards below-average rainfall (decile 3 or lower, indicated by the red shading).
The temperature deciles maps show the typical maximum (left) and minimum (right) temperature impacts during a negative IOD. A negative IOD often results in cooler than average maximum temperatures (decile 3 or lower, indicated by the blue shading) over southeastern mainland Australia. Maximum and minimum temperatures in the far north are typically warmer than average (decile 8 higher), and minimum temperatures above average over southeastern mainland Australia.
The maps above are composites of the moderate to strong positive or negative Indian Ocean Dipole event years, since 1960. They provide guidance on the typical conditions during a moderate to strong event. For each of these event years, the deciles for the winter–spring and summer period are calculated against all years since data was available to the relevant latest month. These deciles are then averaged for each point in Australia, and the result mapped.
Rainfall and temperature in positive or negative Indian Ocean Dipole event years does not follow an identical pattern to the maps above. These maps show average patterns. In reality, each event will be slightly different and it is always possible for areas of below-average rainfall to occur during a negative Indian Ocean Dipole event, or above-average rainfall during positive Indian Ocean Dipole event.