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 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.

Southern Oscillation Index

SOI

Nino3.4 Index

Nino3.4
Display Your Local Weather

Weather News

BOM says deluge across Queensland at levels not seen since Cyclone Debbie

14:10 EDT

The massive downpour across southern Queensland is at levels not seen since Cyclone Debbie hammered the coastline last March, the Bureau of Meteorology (BOM) says.

Man's body found after being swept away in floodwaters near Gympie as wife watched

13:37 EDT

A man's body has been found after his car was swept off a flooded causeway near Gympie in south-east Queensland overnight.

Storm damages WA homes, brings down power lines as winds reach up to 100 kph

10:36 EDT

A strong cold front over the southern half of Western Australia has brought wind gusts of up to 100 kilometres per hour to coastal areas of Perth.