Fairfax Media Network

Agriculture Weather


Southern Oscillation Index

  • location
  • Aus

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 Niņa.

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 Niņo.

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.

Southern Oscillation Index

SOI

Nino3.4 Index

Nino3.4
Display Your Local Weather

Weather News

Melbourne shivers through coldest winter in 26 years, no warm start to Spring in sight

19:19 EST

If you thought Melbourne's winter was colder than usual, you are not wrong.

Tasmania's winter coldest in nearly 50 years, Bureau of Meteorology says

17:25 EST

The Bureau of Meteorology has confirmed what many Tasmanians already suspected, it has been the coldest winter in nearly 50 years.

Katter's Australia Party accuses successive governments of neglecting rural and regional Queenslanders

16:21 EST

Katter's Australia Party MP Shane Knuth says rural Queenslanders have been "done over" by successive governments.