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

Eastern Australia's biggest storm outbreak of the season

12:37 EST

The first significant rain and thunderstorm outbreak of spring will affect eastern and southeastern Australia this week.

Today looks like the last decent day, so here's our 2021 snow season wrap

10:23 EST

The 2021 season snow is not dead quite yet, with lifts still spinning at four resorts – Mt Buller, Falls Creek and Mt Hotham in Victoria, plus Perisher in NSW – but the weather this week will turn ugly from a snow perspective, with several days of rain from about Tuesday onwards.

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!