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

July wrap up around the grounds

16:19 EST

The month of July was quite dynamic across the nation, with some particularly strong cold fronts which delivered low level snow as far north as the Border Ranges, and spells of prolonged dry and warm conditions, particularly along the east coast.

Widespread rain to quench thirsty West Australian crops

16:02 EST

Widespread, drenching rain across many parts of Western Australia's agricultural region, brings a smile to the faces of local farmers.

The Photo Fence: Artists capture Darwin homeowners' love affair with high fences

15:20 EST

Some encase Darwin's homes in a gnarled mesh vestige while others stand like spiked watchmen separating the street from those living inside.