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 automates Townsville Airport Weather Station, infuriating mayors in region

18:54 EDT

The Bureau of Meteorology has apologised to North Queensland mayors who say they are shocked by the automation of a weather office in the cyclone zone despite the promise of further consultation.

Mowing madness after rain brings lush, green grass to south-east Queensland yards

15:44 EDT

It's hot and steamy with the strong smell of two-stroke fuel and grass clippings in the air, while a long line of customers wait to be served at Chris Walden's Bundaberg mower shop in south-east Queensland.

Sydney thunderstorm lights up the night sky as lightning, wind gusts and hail hit NSW

14:35 EDT

A man was killed by a flying gas bottle in Sydney's The Rocks as severe thunderstorms hammered parts of New South Wales overnight.