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
09:50 CST
34°C
27°C
Possible thunderstorm
Weather News
Week-long spring storm outbreak
10:45 EDT
It will be a thundery week across northern and eastern Australia, with daily storms firing up across multiple states and territories.
Psychology and cyclones: Why we don't prepare, and what we can learn from other cultures
17:41 EDT
After a weekend of wild weather and with the cyclone season upon us, it is a good time to ask â?? why do we fail to prepare for the worst? Psychologist and disaster researcher Douglas Paton came to the Top End chasing storms and the answer to that question.
NSW fire update
16:35 EDT
Almost 50 fires are bringing across New South Wales this afternoon according to the state's Rural Fire Service.
