🌊 Bay of Bengal · Spring 2026
Expert seasonal outlook – Neutral ENSO, IOD & monsoon transition
valid March–May 2026
Dr. A. N. Sharma
Indian Meteorological Expert
North Bay
- Early heat: 36–39°C late Mar [citation:1][citation:9]
- Kalbaishakhi: Severe nor'westers, hail, 2-3 storm days [citation:1]
- Heatwaves: 3-5 mild/mod + 1-2 severe (Apr–May) [citation:4]
- Rain: Isolated thundershowers, normal March rainfall [citation:1]
Central Bay
- Mar fair weather: Generally fair, a few clouds [citation:5]
- SST rise: Rapid heating from April, convective lift
- Thunder: Increasing lightning & nor'westers late March
- Low pressure: 2‑3 systems form Apr–May; 1 may cyclone [citation:1][citation:4]
South Bay
- Equatorial feed: Moisture from Madagascar/Indian Ocean [citation:2]
- SST: 29–30°C, conducive for organized convection
- Genesis region: 10–15°N peak cyclone density [citation:3]
- Wyrtki Jet: Semiannual jet strengthens IOD teleconnections [citation:2]
East Bay
- Early rains: Heavy rainfall anomaly triggers IOD? [citation:6][citation:10]
- Cross‑equatorial: Southerly anomalies off Sumatra [citation:10]
- Local: Partly cloudy, isolated light rain (Myanmar) [citation:5]
- Sea level: IOD‑related Rossby waves impact coast [citation:2]
Drivers & heating
Hot arid air – Arabia — Intrusion of dry continental air from west/northwest India in March, spikes temperatures (heatwave conditions) over northwest Bay and adjoining land [citation:1][citation:4].
Madagascar/Equator inflow — Moist cross‑equatorial flow from the south Indian Ocean feeds the monsoon trough; enhances convective instability over south‑central Bay by late spring [citation:2].
Wyrtki Jets & IOD — Spring Wyrtki Jets (semiannual) transport warm water east; positive IOD would cool east equatorial but currently neutral. Strong east Bay rains may trigger IOD‑like cooling [citation:6][citation:10].
Seasonal heating / convection lift
⬆️ Gradual SST increase & latent heat flux fuels thunderstorm activity [citation:1][citation:4]
IOD Spring influence
- Negative IOD → stronger Wyrtki Jet, sea‑level rise along east India/Bangladesh [citation:2].
- Positive IOD → suppresses Bay cyclone genesis? but neutral IOD expected in spring (ensuing summer may develop).
- Rainfall over east Bay in early summer can cool Sumatra waters, triggering IOD [citation:6][citation:10].
Temp / Cyclone parameters
| Region | Mar max (°C) | Apr–May potential |
|---|---|---|
| North Bay | 33–36 | 40°+ severe heatwave [citation:4] |
| Central Bay | 32–34 | 36–38 (SST) |
| South Bay | 30–32 | ~30 SST |
| East Bay | 34–37 (Myanmar) | 38 possible [citation:5] |
🌀 Cyclone climatology (BoB 1891–2020)
| ENSO phase | BoB frequency (annual avg) | Spring relevance |
|---|---|---|
| El Niño | higher in NIO basin [citation:3] | often more AS, BoB moderate |
| La Niña | favours BoB cyclones [citation:3][citation:7] | not expected 2026 |
| NEUTRAL (nENSO) | ~4.03 annual mean | baseline activity, no strong suppression/enhancement |
🌿 IOD effect: Neutral IOD (noIOD) yields ~4.03 cyclones/yr over BoB; positive IOD shifts to AS [citation:3][citation:7].
MJO & storm predictions – spring/summer 2026
2–3
low pressure systems (Apr–May) [citation:1][citation:4]
low pressure systems (Apr–May) [citation:1][citation:4]
1
likely cyclone (Apr–May) [citation:1][citation:4]
likely cyclone (Apr–May) [citation:1][citation:4]
~4
annual average (neutral ENSO) [citation:3][citation:7]
annual average (neutral ENSO) [citation:3][citation:7]
- MJO: spring passage over Indian Ocean (phases 2-3) enhances convection in Bay.
- Typhoon potential: pre‑monsoon cyclones (April/May) typically form in central/south BoB.
- ENSO neutral: no strong suppression; number near long‑term mean (neither El Niño nor La Niña) [citation:3][citation:7].
- Genesis density: 10–15°N band favoured [citation:3].
⏳ Spring into summer transition: With gradual heating, convection lifts & the monsoon flow establishes by early June. MJO pulses in May can trigger rapid intensification. The ongoing neutral ENSO (+ possible negative IOD tendency) suggests near‑normal storm frequency, but warm Bay SST (31°C+ by May) always poses risk of a severe cyclone if atmospheric conditions align [citation:3][citation:7].
🇮🇳 Indian Monsoon look‑ahead
By late May, cross‑equatorial flow strengthens. Neutral IOD/ENSO suggests near‑normal onset around Kerala coast (1 June ±). Bay branch feeds enhanced rainfall over northeast India, Bangladesh & Myanmar by mid‑June.
Quick spring risks
- Severe nor’westers (Kalbaishakhi) – Mar/Apr [citation:1][citation:9]
- Heatwaves – 3‑5 episodes [citation:4]
- One potential cyclone (Apr/May) [citation:1][citation:4]
- MJO enhanced storm spawning in May
- Possible for East BoB thunderstorms in spring if humid and coastal areas heat with increased CAPE and trigger mechanism.