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

Warning for giant hail in QLD and NSW on Wednesday

14:33 EDT

One day after record-breaking hail fell near Mackay, more supercell thunderstorms are again assaulting parts of central Queensland and northern NSW today.

Hot and cold airmasses having a big stoush over South Australia

11:31 EDT

If the weather in South Australia today was a schoolyard brawl, the script would more or less read, "I'm tougher than you!" followed by, "No way, I'm tougher than you!" What's actually happening over SA today is a classic spring weather pattern, whereby warm air from the interior of the country is being pushed across the state ahead of a cold front approaching from the west.

Get a sneak peak into the new Weatherzone Beta website experience while we continue to build out its full functionality.
Explore new datasets, map layers, 7-day charts, 12-month trends and much more!