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
13:00 CST
32°C
23°C
Mostly sunny
Weather News
Will we have a good snow season this year?
10:45 EST
There were two decent rounds of alpine snow last month and much of Australia's southeast shivered through their coldest temperatures in at least six months last week.
Colder showery change moving through southern states
16:08 EST
A front is bringing a colder showery change to southern Australia, dropping temperatures by five-to-10 degrees.
North Queensland chills
09:54 EST
Some inland areas of Northern Queensland have had their coldest April morning in at least 60 years.
