Southern Oscillation Index
The Southern Oscillation Index (SOI) is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
A strongly and consistently positive SOI pattern (e.g. consistently above about +6 over a two month period) is related to a high probability of above the long-term average (median) rainfall for many areas of Australia, especially areas of eastern Australia (including northern Tasmania) - La Niña.
Conversely, a 'deep' and consistently negative SOI pattern (less than about minus 6 over a two month period, with little change over that period) is related to a high probability of below median rainfall for many areas of Australia at certain times of the year - El Niño.
However, it is important to remember that the pattern of relationship between SOI and rainfall (and temperature) can vary depending on the particular season and region. Additionally, the change in SOI over a specified period can be as important in understanding relationships between SOI and rainfall as is the absolute value in SOI.
Now Temperature
At Darwin Ap
10:30 CST
29°C
25°C
Possible thunderstorm
Weather News
NSW weather: Foreign student swept off Nobbys Beach rocks remains missing
10:43 EDT
A man remains missing after being swept off rocks and into the sea at Nobbys Beach at Newcastle in the New South Wales Hunter region.
Wet start of the week coming to Melbourne
13:46 EDT
Stunning sunny skies across Victoria are about to give way to wet weather, especially in the south.
Wet and wild week for coastal Queensland
12:52 EDT
With a lingering coastal trough and developing low pressure system, the coming week is set to be soaking and thundery for many parts of the Queensland coastal fringe.
