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

Lines of severe storms hitting SA, with more dangerous weather on the way

10:16 EDT

Several lines of heavy rain and severe thunderstorms are moving over southern districts of SA this morning, kicking off two days of dangerous weather in southern Australia.

Thunderstorm asthma warning as storms set to lash Victoria

22:50 EDT

A severe weather warning and thunderstorm asthma alert has been issued for parts of Victoria today, with rain and winds expected to lash the state.

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!