What Happened
- Global climate agencies have issued warnings about a likely El Niño event developing in summer 2026, with the potential for it to be stronger than earlier forecast.
- Data from 1980 onwards shows that approximately 70% of El Niño years have coincided with below-normal Indian monsoon rainfall.
- Despite the dominant statistical pattern, occasional offsetting factors — particularly a positive Indian Ocean Dipole (IOD) — have historically cushioned the monsoon impact.
- The southwest monsoon for 2026 is projected by IMD at 92–94% of the long-period average (LPA), placing it in the "below normal" category.
- The overall monsoon outlook for 2026 remains uncertain, dependent on how multiple interacting climate forces evolve through May and June.
Static Topic Bridges
El Niño–Southern Oscillation (ENSO) and Its Mechanism
El Niño is a periodic warming of sea surface temperatures (SST) in the central and eastern equatorial Pacific Ocean, occurring every 3–7 years and lasting 9–12 months on average. It is one phase of the broader El Niño–Southern Oscillation (ENSO) system, which also includes La Niña (periodic cooling of the same region) and a neutral phase. The term "Southern Oscillation" refers to the see-saw pattern of atmospheric pressure between the eastern Pacific (near Tahiti) and the western Pacific (near Darwin, Australia), first documented by Sir Gilbert Walker in the early 20th century.
- During El Niño, weakened easterly trade winds allow warm Pacific waters to migrate eastward, suppressing the Walker Circulation (the large east-west atmospheric loop over the Pacific).
- The weakening of the Walker Circulation reduces convective activity over the western Pacific and Indian Ocean, which in turn weakens the moisture-laden monsoon winds reaching India.
- About 60–70% of El Niño years historically coincide with below-normal Indian summer monsoon rainfall (ISMR).
- El Niño events are monitored using the Oceanic Niño Index (ONI) — a 3-month running mean of SST anomalies in the Niño 3.4 region (5°N–5°S, 120°W–170°W). An ONI of +0.5°C or above for 5 consecutive overlapping 3-month periods is classified as El Niño.
- The Bjerknes feedback (named after Jacob Bjerknes, 1969) is the self-reinforcing positive feedback loop that amplifies ENSO events.
Connection to this news: A developing El Niño event in 2026 raises the probability of a below-normal monsoon, threatening agricultural output, food prices, and rural demand — consistent with historical data showing 70% correlation with weak monsoons.
Indian Ocean Dipole (IOD) — The Monsoon Mitigator
The Indian Ocean Dipole (IOD) is a coupled ocean-atmosphere phenomenon in the Indian Ocean, characterized by anomalous warming in the western Indian Ocean (near the Arabian Sea and East Africa) and cooling in the eastern Indian Ocean (near Indonesia). It operates somewhat independently of ENSO, though the two interact. A positive IOD (warm west, cool east) generally enhances Indian monsoon rainfall, while a negative IOD suppresses it.
- IOD was first described scientifically by Saji et al. in 1999.
- It is measured by the Dipole Mode Index (DMI) — the difference in SST anomaly between the western pole (50°E–70°E, 10°S–10°N) and the eastern pole (90°E–110°E, 10°S–0°N).
- A positive IOD can offset or mitigate a concurrent El Niño's suppressive effect on the monsoon — as happened in 2019, when a strong positive IOD helped India receive above-normal monsoon rainfall despite concurrent El Niño conditions.
- IOD typically develops between April–May and peaks in September–October, dissipating after the ITCZ retreats.
Connection to this news: Even if El Niño materialises in 2026, its impact on the Indian monsoon depends significantly on whether the IOD develops a positive phase. A neutral or negative IOD concurrent with El Niño would compound monsoon weakness; a positive IOD could partially offset it.
Indian Summer Monsoon — Mechanism and ITCZ
The Indian Summer Monsoon (ISM) — also called the Southwest Monsoon — is driven by the differential heating of the Indian landmass and the Indian Ocean between March and September. The Intertropical Convergence Zone (ITCZ) — the band of low pressure near the equator where northeast and southeast trade winds converge — migrates northward over India in June, triggering the monsoon onset at Kerala around June 1. The monsoon accounts for 70–80% of India's annual rainfall and irrigates roughly half of the country's total cultivated area.
- Long-Period Average (LPA) of the Indian summer monsoon: 87 cm (defined over the period 1971–2020); IMD classifies below-normal as 90–95% of LPA.
- IMD issues a first advance forecast for the monsoon around mid-April, which is when early El Niño signals are factored in.
- Key monsoon drivers: Arabian Sea branch (arrives Kerala first), Bay of Bengal branch (advances northeast), and the Somali Jet.
- Deficient rainfall years (< 90% LPA) have historically seen reduced Kharif output, higher food inflation, and reduced rural incomes.
Connection to this news: A monsoon projected at 92–94% LPA qualifies as below-normal — if El Niño strengthens and no offsetting IOD develops, actual rainfall could fall below the 90% threshold into "deficient" territory.
Monsoon-Agriculture-Inflation Linkage (Economics Bridge)
The Indian monsoon has a direct transmission mechanism to macroeconomic variables: rainfall deficiency → reduced Kharif production → lower agricultural GVA → higher food prices → elevated CPI inflation → RBI policy constraint. El Niño years in which Kharif is significantly impacted show an average contraction of ~5.4% in Kharif output and ~0.3% decline in agricultural GVA growth.
- Food and beverages weight in the CPI basket: approximately 39.06% (CPI base year 2012; revision to base year 2024 underway).
- A 6–10% spike in food prices from weak Kharif can push headline CPI to 5.5–7%, above RBI's upper tolerance band of 6%.
- RBI's inflation targeting framework (Finance Act 2016, RBI Act Section 45ZA) mandates keeping CPI inflation at 4% ± 2%.
- MSP (Minimum Support Price) interventions, announced by the Cabinet on the recommendation of the Commission for Agricultural Costs and Prices (CACP), are used to support farmer income during deficient monsoon years.
Connection to this news: A below-normal monsoon in 2026, compounded by existing Gulf-driven supply chain disruptions, risks pushing food inflation above the RBI's comfort zone and constraining monetary policy space.
Key Facts & Data
- Percentage of El Niño years (since 1980) linked to below-normal Indian monsoon: ~70%
- IMD's 2026 monsoon forecast: 92–94% of LPA (below normal; LPA = 87 cm over 1971–2020 base)
- ENSO monitoring threshold: ONI of +0.5°C over 5 consecutive 3-month periods = El Niño
- IOD first described: 1999 (Saji et al.)
- Historical El Niño average impact: ~5.4% contraction in Kharif production, ~0.3% decline in agricultural GVA growth
- Food and beverages weight in CPI basket: ~39%
- RBI inflation target: 4% ± 2% (upper tolerance: 6%)