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
11:20 CST
32°C
24°C
Possible thunderstorm
Weather News
Vigorous cold front blasts the southeast
12:02 EST
A strong cold front is making its presence felt as it continues its march across the southeast.
Late-season tropical activity
09:42 EST
With tropical cyclone season soon to wrap up, Australian and nearby tropical waters have seen a surge in cyclone activity late in the season.
West coast of Australia the place to be this weekend
09:54 EST
West coast of Australia the place to be this weekend With cold and stormy weather affecting the southern and southeastern parts of the country in coming days, while residual flooding and strong winds still plague the east, it looks like the best beach weather can be found along the west coast.
