Indian Ocean Dipole 2025

Resulting IOD currently, cloud over WA.

1. What a Negative IOD Is

The Indian Ocean Dipole (IOD) is like a “see-saw” of sea temperatures between Africa and Indonesia.

Negative IOD = cooler waters near Africa, warmer waters near Indonesia and northwest Australia.

Warm water near us means more moisture evaporates into the atmosphere → more cloud and rain.

You can see in the diagram: warm seas to our northwest drive rising air and rainfall over northern and eastern Australia.

2. How It Affects Rainfall

The rainfall map shows average conditions across nine past negative IOD years (like 2010, 2016, 2022):

Blue/purple areas = wetter than normal. This covers much of eastern, southern and inland Australia.

Green areas = a bit wetter than normal.

Only tiny parts of WA and SA dip into drier (yellow) zones.

In short: a negative IOD loads the dice for a wetter winter and spring across most of the country.

3. The Current Situation

The IOD index graph tracks how strong it is:

Values below –0.4°C = a negative IOD is active.

As of mid-August 2025, the index is sitting at around –0.91°C, which is firmly negative.

That means we’re currently in a negative IOD phase heading into spring and summer.

4. What It Means for Cyclone Season

Warm seas near Australia = more cyclone fuel. Cyclones feed on warm, moist air rising from the ocean.

Negative IOD years tend to bring wetter northern Australia. That means any cyclones that do form have a better chance of producing heavy rainfall and flooding.

It doesn’t guarantee more cyclones, but it tilts the odds toward a busier and wetter season, especially for northern WA, NT, and Queensland.

Plain Summary:

Right now, the Indian Ocean is in a negative IOD. That’s why we can expect wetter conditions across much of Australia through spring. As cyclone season approaches, the warmer seas to our northwest act like extra fuel, raising the risk of wetter, stronger tropical systems over northern Australia. It’s a climate pattern that makes us more vulnerable to flooding rains and cyclones, even if it doesn’t change the total cyclone count much.