| Month | DMI | West pole | East pole |
|---|---|---|---|
| 2025-04 | +0.25 | +0.47 | +0.22 |
| 2025-05 | +0.25 | +0.56 | +0.30 |
| 2025-06 | +0.08 | +0.57 | +0.49 |
| 2025-07 | -0.12 | +0.52 | +0.64 |
| 2025-08 | -0.60 | +0.16 | +0.76 |
| 2025-09 | -0.71 | +0.07 | +0.78 |
| 2025-10 | -1.12 | -0.16 | +0.96 |
| 2025-11 | -0.59 | -0.19 | +0.40 |
| 2025-12 | -0.26 | +0.20 | +0.46 |
| 2026-01 | +0.20 | +0.17 | -0.03 |
| 2026-02 | +0.67 | +0.42 | -0.25 |
| 2026-03 | +0.15 | +0.34 | +0.18 |
| 2026-04 | +0.18 | +0.45 | +0.28 |
| 2026-05 | -0.35 | +0.21 | +0.56 |
| 2026-06 | -0.15 | +0.83 | +0.98 |
Orange band = positive IOD (DMI ≥ +0.4°C: warm west / cool east). Blue band = negative IOD (DMI ≤ −0.4°C). An event requires the threshold to be sustained ~2 months within the May–Nov active season — single months are too noisy. Source: NOAA OISST v2.1, self-computed (Saji 1999 / BOM boxes).
The DMI is the difference of two SST-anomaly boxes. The east pole (off Sumatra/Java) is the noisy one — wind- and upwelling-driven, it can swing on a single storm and fake a dipole. The west pole is more inertial. Watching them separately tells you whether a move is a real coupled shift or just east-pole noise.
The IOD is seasonally phase-locked: the spread (σ) collapses in boreal winter and spring, when the index is near-zero residual gradient, then opens up May–Nov as the coupled mode develops and peaks. A DMI value in February means little; the same value in October is a developing event. This is why we season-gate.
| Commodity / Region | Positive IOD Effect | Negative IOD Effect |
|---|---|---|
| East Africa Arabica (Ethiopia, Kenya, Tanzania) |
Supply supportive
Enhanced Oct–Dec short rains — generally supportive of yield, but flood & coffee-leaf-rust risk in strong events.
|
Supply risk
Suppressed short rains → drought stress on arabica and food crops across the Horn.
|
| SE Asia Robusta (Vietnam, Indonesia) |
Supply risk
Drier over the maritime continent — moisture stress for robusta in strong positive events.
|
Supply supportive
Wetter across Indonesia/Indochina — generally favorable soil moisture for robusta.
|
| Australian Wheat |
Supply risk
Drier across eastern & southern cropping zones — a primary positive-IOD supply risk.
|
Supply supportive
Wetter, more favorable conditions across the wheat belt — supportive of supply.
|
| Indian Monsoon (cotton, sugar, pulses) |
Supply supportive
Tends to support / offset monsoon rainfall — can buffer an El Niño-driven deficit.
|
Supply risk
Tends to weaken the monsoon — dry stress risk for kharif crops.
|
| Indonesian Palm / Cocoa |
Supply risk
Drier maritime continent — moisture stress risk in strong events.
|
Supply supportive
Wetter — generally favorable.
|
| Phase | Strength | Start | End | Months | Peak DMI |
|---|---|---|---|---|---|
| Negative IOD | Strong | 2025-08 | 2025-11 | 4 | -1.12°C |
| Negative IOD | Weak | 2024-10 | 2024-11 | 2 | -0.59°C |
| Positive IOD | Strong | 2023-08 | 2023-11 | 4 | +1.38°C |
| Negative IOD | Moderate | 2022-05 | 2022-10 | 6 | -0.93°C |
| Negative IOD | Weak | 2020-08 | 2020-09 | 2 | -0.45°C |
| Positive IOD | Weak | 2020-05 | 2020-06 | 2 | +0.61°C |
| Positive IOD | Strong | 2019-05 | 2019-11 | 7 | +1.74°C |
| Positive IOD | Moderate | 2017-05 | 2017-08 | 4 | +0.77°C |
| Negative IOD | Strong | 2016-05 | 2016-10 | 6 | -1.15°C |
| Positive IOD | Moderate | 2015-08 | 2015-10 | 3 | +0.94°C |
| Positive IOD | Moderate | 2012-07 | 2012-09 | 3 | +0.91°C |
| Negative IOD | Strong | 2010-09 | 2010-11 | 3 | -1.03°C |
| Negative IOD | Weak | 2009-07 | 2009-08 | 2 | -0.46°C |
| Positive IOD | Moderate | 2006-09 | 2006-11 | 3 | +0.95°C |
| Negative IOD | Weak | 2005-07 | 2005-10 | 4 | -0.55°C |
| Negative IOD | Weak | 2004-06 | 2004-07 | 2 | -0.47°C |