" Southern Oscillation Index
Other Elders Sites About
NSW/ACT Sun 04:10 EST: Coastal Wind Warning   Sun 02:38 EST: Sheep Graziers Warning   Sat 17:16 EST: Flood Warning - Belubula River   Sat 10:25 EST: Flood Warning - Bogan River   Sat 09:58 EST: Flood Warning - MacQuarie River   Sat 08:54 EST: Flood Warning - Lachlan River   Queensland Sat 11:08 EST: Flood Warning - Thomson/Barcoo/Cooper Ck   Fri 13:52 EST: Flood Warning - Fitzroy River   Fri 10:33 EST: Flood Warning - Diamantina River   Fri 08:13 EST: Flood Warning - Burdekin River   South Australia Sat 22:57 CST: Sheep Graziers Warning   Sat 22:00 CST: Coastal Wind Warning   Tasmania Sun 05:00 EST: Coastal Wind Warning   Sun 03:59 EST: Road Weather Alert   Sat 22:15 EST: Bushwalking Alert   Sat 22:15 EST: Sheep Graziers Warning   Sat 19:29 EST: Flood Warning - South Esk   Sat 16:35 EST: Flood Warning - Derwent River   Sat 16:01 EST: Flood Warning - North Esk River   Sat 15:56 EST: Flood Warning - Macquarie   Sat 15:30 EST: Flood Warning - Meander River   Sat 08:43 EST: Flood Warning - Jordan River   Victoria Sun 05:10 EST: Coastal Strong Wind/Gale Warning   Sat 20:25 EST: Flood Warning - Mitchell River   Sat 17:53 EST: Flood Warning - Murray River upstream of Hume Weir   Sat 17:36 EST: Flood Warning - Kiewa River   Sat 17:12 EST: Flood Warning - King River   Sat 16:50 EST: Flood Warning - Goulburn River   Sat 16:44 EST: Flood Warning - Macalister River   Sat 16:00 EST: Flood warning for Seven Creeks / Castle Creek   Sat 12:23 EST: Flood Advice - North East Victoria   Sat 10:04 EST: Flood Warning - Mitta Mitta River   Sat 05:51 EST: Flood Warning - Westernport   Western Australia Sat 22:00 WST: Coastal Wind Warning  

Southern Oscillation Index

Weekly / Monthly
Southern Oscillation Index

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 Niņa.

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 Niņo.

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.