Weak monsoon, El Niño to take a tenth of India’s hydro power generation offline

The India Meteorological Department (IMD) has revised its 2026 southwest monsoon forecast down to 90% of the Long Period Average (LPA) — placing the outlook ...

What Happened

The India Meteorological Department (IMD) has revised its 2026 southwest monsoon forecast down to 90% of the Long Period Average (LPA) — placing the outlook in the "below normal" category — from an earlier April estimate of 92% of LPA.
The downgrade is primarily linked to the anticipated emergence of El Niño conditions in the equatorial Pacific, which historically correlates with deficient rainfall over the Indian subcontinent.
A positive Indian Ocean Dipole (IOD) provides partial mitigation, keeping the forecast at "below normal" rather than "deficient."
With weaker monsoon rains reducing reservoir inflows, India's hydropower generation in 2026 may be approximately 10% lower than 2025 levels.
Lower hydropower output puts pressure on the thermal power system, raising coal demand during a period of high summer cooling loads.

Static Topic Bridges

El Niño–Southern Oscillation (ENSO) Cycle

El Niño is a phase of the El Niño–Southern Oscillation (ENSO) cycle — a coupled ocean-atmosphere climate pattern in the tropical Pacific. During El Niño, the central and eastern equatorial Pacific Ocean warms anomalously (sea surface temperatures rise 0.5°C or more above the 30-year average), weakening trade winds and altering global atmospheric circulation. The three phases of ENSO are: El Niño (warm phase), La Niña (cool phase), and ENSO Neutral. El Niño events typically occur every 2–7 years and last 9–12 months.

El Niño suppresses India's southwest monsoon by shifting the ascending branch of the Hadley circulation eastward, reducing moisture convergence over South Asia.
The Walker Circulation weakens during El Niño, reducing the pressure gradient that drives monsoon winds.
Historical correlation: Major El Niño years (1987, 2002, 2009, 2015) were associated with below-normal or deficient monsoons in India.
La Niña typically brings above-normal monsoon rainfall to India.

Connection to this news: IMD's 2026 monsoon downgrade is directly driven by anticipated El Niño development, creating the primary climate risk to agricultural and energy sectors.

Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD) is an ocean-atmosphere interaction in the Indian Ocean, analogous to ENSO in the Pacific. During a positive IOD, the western Indian Ocean (near East Africa) is warmer than the eastern Indian Ocean (near Indonesia). A positive IOD enhances moisture supply to the Indian subcontinent, partially counteracting the negative effects of El Niño on the Indian monsoon.

A positive IOD strengthens westerlies and increases rainfall over peninsular India and Sri Lanka.
A negative IOD amplifies El Niño's drought-inducing effects over India.
The 2019 season showed a strong positive IOD offsetting El Niño effects — a key example cited in UPSC contexts.
IMD incorporates IOD indices alongside ENSO indices in its seasonal forecast models.

Connection to this news: The 2026 positive IOD is the reason IMD forecasts "below normal" rather than "deficient" monsoon, even with El Niño emerging — a nuanced interaction directly testable in Mains.

IMD Forecasting Methodology and Long Period Average (LPA)

The India Meteorological Department (IMD) issues two-stage seasonal forecasts: a long-range forecast in April and an updated forecast in May/June. Rainfall is measured as a percentage of the Long Period Average (LPA) — the 50-year average of June–September rainfall over the country (currently set at ~87 cm). IMD categorizes monsoon performance as: Normal (96–104% of LPA), Above Normal (>104%), Below Normal (90–96%), Deficient (<90%), and Excess (>110%).

90% of LPA = "Below Normal" — the 2026 IMD downgraded forecast.
IMD uses statistical and dynamical models, incorporating ENSO, IOD, Eurasian snow cover, and North Atlantic SST indices.
IMD is under the Ministry of Earth Sciences.
District-level forecasts and agro-met advisories help farmers plan sowing dates and crop choices.

Connection to this news: The article's "90% of the 50-year average" figure is the IMD LPA benchmark — a standard Prelims data point.

India's Hydropower Capacity and Monsoon Dependence

India's hydropower generation is heavily dependent on monsoon-fed reservoir levels. As of late 2025, India's installed large hydropower capacity was approximately 50,414 MW (~50 GW), with an additional ~5,159 MW of small hydro — making total installed hydropower capacity over 55 GW. NHPC Limited is the primary public sector hydropower utility. India also has 10 operational pumped storage projects (7,175 MW) with 10 more under construction (11,620 MW).

Hydropower accounts for approximately 11–12% of India's total installed electricity capacity (as of 2025–26).
Hydropower generation is seasonal — heavily concentrated in the July–October monsoon period; reservoirs store water for dry-season generation.
A 10% decline in hydropower output increases dependence on coal-based thermal power, impacting fuel logistics and emissions.
NHPC is expanding its capacity from 8.2 GW to ~13 GW by FY2026-27, with the 2,000 MW Subansiri Lower Project anchoring near-term additions.
The National Electricity Policy 2005 designates hydropower as a preferred clean energy source; the government has set a target of 100 GW of pumped storage in its long-term roadmap.

Connection to this news: A weak 2026 monsoon directly reduces reservoir inflows, cutting run-of-river generation and limiting storage-based dispatch — the 10% generation shortfall estimate reflects this seasonal dependence.

Key Facts & Data

2026 IMD monsoon forecast: 90% of LPA (below normal; revised down from 92%)
LPA definition: 50-year average of June–September all-India rainfall (~87 cm)
IMD categories: Deficient <90%, Below Normal 90–96%, Normal 96–104% of LPA
El Niño mechanism: Warming of central-eastern equatorial Pacific; suppresses Indian monsoon via weakened Walker Circulation
IOD (positive): Warms western Indian Ocean; partially offsets El Niño's negative monsoon impact
India's installed large hydro capacity (Nov 2025): ~50,414 MW
India's small hydro capacity (Nov 2025): ~5,159 MW
Pumped storage projects (operational): 10 projects, 7,175 MW
Projected hydropower generation decline in 2026: ~10% below 2025 levels
NHPC expansion target: 8.2 GW → ~13 GW by FY2026-27
Ministry of Earth Sciences: Nodal ministry for IMD
Ministry of Power / NHPC: Primary hydropower governance