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
20:10 CST
26°C
33°C
Thunderstorms
Weather News
Renewable energy mix played role in SA blackout, third AEMO report confirms
18:19 EDT
South Australia's renewables-heavy power mix was a factor in the statewide blackout in September, a new report by the Australian Energy Market Operator (AEMO) has confirmed.
Australia's cherry season predicted to be expensive after unseasonably cold weather
18:04 EDT
Cherries from farms in Tasmania, Victoria, New South Wales and South Australia will be the "most expensive ever grown in history", says the president of the Cherry Growers Association of Australia.
Western storms intensify
17:26 EDT
Severe thunderstorms are lashing parts of Western Australia today.
