Indian Ocean Dipole [IOD Index]



Teleconnections and long range forecasts
10 hPa Temp/Geop
100 hPa Temp/Geop
AAO Index
Strato Analysis
AO Index
EA Index
EA/WR Index
IOD Index
MJO Index
NAO Index
Intraseas. Osc.
PDO Index
PNA Index
POL Index
North Pole Strato
QBO Index
SCAND Index
SOI Index
SST (Sea Temp)

The Role of the Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD) is an irregular oscillation of sea surface temperatures in which the western Indian Ocean (near the Horn of Africa) becomes alternately warmer or colder than the eastern part of the basin (northwest of Australia and near Indonesia).

Just as ENSO (El Niño and La Niña) dominates the Pacific Ocean, the IOD dominates the Indian Ocean and has a profound impact on global rainfall patterns. The IOD has three phases:

  • Positive IOD: Above-average temperatures in the west and below-average in the east. It brings intense rainfall (and sometimes flooding) to East Africa, while causing severe drought and bushfire risks in Indonesia and Australia.
  • Negative IOD: The situation reverses. Cold waters in the west and warm in the east, bringing enormous amounts of rain to Australia and very dry weather to East Africa.
  • Neutral: No significant thermal gradient between east and west.

Interaction with Europe: Although the epicenter of the phenomenon is far from Europe, the tropical convection anomalies of the IOD trigger powerful atmospheric wave trains (Rossby waves) that alter the jet streams. A strongly positive IOD in autumn tends to reinforce the stratospheric Polar Vortex, laying the groundwork for a mild European winter, characterized by strong Atlantic westerlies. Conversely, a negative IOD favors a weak Polar Vortex, increasing the chances of cold waves in Eurasia.

IOD Trend (Last 48 Months)

Data acquired and processed in real-time from the NOAA CPC DMI index (Extended Reconstructed Sea Surface Temperature).

Expected Impacts (Trends)

Positive Phase (IOD+)

DMI average value (last 3 months): 0.59 °C

The IOD index is currently in a positive phase. The western Indian Ocean (near Africa) is warmer than normal, while the eastern part (near Australia) is cooler. Globally, this brings heavy rainfall to East Africa and drought or bushfires to Indonesia and Australia. For Europe, a positive IOD (especially in autumn/winter) often favors a strengthening of the Polar Vortex, leading to milder and more zonal winters, with fewer continental cold outbreaks.