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
10:50 CST
34°C
27°C
Possible thunderstorm
Weather News
Hot summer starting with a heatwave in NSW
12:28 EDT
Parts of New South Wales could have their hottest weather in two-to-three years during the opening week of summer.
BOM forecasts southern Queensland heatwave with temperatures possibly hitting 40C
11:53 EDT
Severe-to-extreme heatwave conditions are predicted to hit southern Queensland for three days from Friday, with temperatures forecast to crack 40 degrees Celsius in some parts of the state.
Queensland farmer weathers the storm, literally and financially, during bad weather
09:54 EDT
A Queensland lettuce farmer says having two properties to grow his lettuce on helps to offset the risks of the summer storm season.
