IMD makes downward revision in monsoon forecast, India headed for driest year in a decade

The India Meteorological Department (IMD) issued its second-stage (updated) forecast for the 2026 Southwest Monsoon season (June–September), revising project...

What Happened

The India Meteorological Department (IMD) issued its second-stage (updated) forecast for the 2026 Southwest Monsoon season (June–September), revising projected rainfall downward to 90% of the Long Period Average (LPA) — a further downgrade from the April first-stage estimate of 92% of LPA.
At 90% of LPA, the 2026 monsoon falls in the "below normal" category under IMD's classification — meaning India faces a higher-than-usual probability of agricultural stress and water scarcity across the monsoon core zone.
The primary driver of the downgrade is the anticipated emergence of El Niño conditions in the Equatorial Pacific Ocean; the probability of El Niño developing was assessed at 82% by June, rising above 90% during July and August — the peak monsoon months.
The monsoon core zone — which encompasses most of India's rain-fed agricultural area — is most likely to receive below 94% of LPA, threatening production of kharif pulses, oilseeds, and sugarcane.
If realised, this would make 2026 the driest monsoon year in approximately a decade; the last comparable below-normal year was 2023 (another El Niño year), when the season recorded 94% of LPA.

Static Topic Bridges

Southwest Monsoon — Mechanism, Onset, and Withdrawal

The Southwest (SW) Monsoon is India's primary rainfall system, delivering approximately 70–75% of India's annual precipitation between June and September. It originates from moisture-laden winds from the Indian Ocean and the Bay of Bengal, driven by a pressure differential between the high-pressure cell over the Indian Ocean and the thermal low over the Indian subcontinent (Thar Desert region). The monsoon arrives in two branches: the Arabian Sea branch (hits Kerala around June 1, then moves up the west coast) and the Bay of Bengal branch (moves northeast India first, then curves westward).

Normal onset over Kerala: June 1 (with a variability of ±7 days).
Normal withdrawal from northwest Rajasthan: around September 17; complete withdrawal from India: around October 15.
The four months June to September are officially the "Southwest Monsoon Season."
The monsoon interacts with the Western Ghats (orographic rainfall), the Bay of Bengal branch, and cyclonic systems — making India's regional rainfall distribution highly variable.
Northeast Monsoon (October–December) provides critical rainfall to Tamil Nadu, Puducherry, Coastal Andhra Pradesh, and Sri Lanka — but is secondary in national water budget terms.

Connection to this news: The IMD's forecast revision applies to the Southwest Monsoon season (June–September) — the period that determines India's kharif crop outcomes, reservoir levels, groundwater recharge, and therefore food prices and rural incomes.

Long Period Average (LPA) — IMD's Benchmark

The Long Period Average (LPA) is the benchmark against which seasonal monsoon rainfall is measured. IMD currently defines LPA as the average rainfall over India during June–September based on data from 1971 to 2020. The current LPA is approximately 868.6 mm.

IMD rainfall categories relative to LPA:
Above Normal: ≥ 110% of LPA
Normal: 96–110% of LPA
Below Normal: 90–95% of LPA
Deficient: < 90% of LPA
Excess: > 120% of LPA (sub-divisional classification differs slightly)
At 90% of LPA (model error ±4%), the 2026 forecast places India right at the boundary between "below normal" and "deficient" — implying a meaningful probability of deficient rainfall in some regions.
LPA is updated periodically; earlier LPA (1961–2010) was 890 mm; the revised 1971–2020 baseline reflects cooling/wetting trends and is the current standard.
IMD issues two-stage long-range forecasts: Stage 1 in April (seasonal total), Stage 2 / update in late May (refined seasonal and regional outlooks).

Connection to this news: The IMD's downward revision from 92% to 90% of LPA in the second-stage forecast reflects updated ocean temperature data showing faster El Niño development — a shift from the April assessment when ENSO conditions were still borderline neutral-to-weak El Niño.

El Niño–Southern Oscillation (ENSO) and Indian Monsoon

ENSO (El Niño–Southern Oscillation) is a periodic climate pattern involving anomalous warming (El Niño) or cooling (La Niña) of sea surface temperatures in the central and eastern equatorial Pacific Ocean. El Niño events suppress the Indian Southwest Monsoon because the warm Pacific draws moisture and convective activity away from the Indian Ocean basin, weakening the monsoon circulation.

El Niño: Characterised by SSTs in the Niño 3.4 region (central-eastern Pacific) exceeding +0.5°C above average for at least five consecutive overlapping three-month periods.
La Niña: SSTs below -0.5°C in the same region; typically associated with above-normal Indian monsoon rainfall.
ENSO Neutral: SSTs within ±0.5°C; Indian monsoon tends to be near-normal.
Historical correlation: ~60–65% of El Niño years have seen below-normal or deficient Indian monsoon rainfall; the relationship is strong but not deterministic (the 2019 El Niño year, for instance, recorded near-normal rainfall in India).
The Indian Ocean Dipole (IOD) — a positive IOD event (warm western Indian Ocean) — can partially offset El Niño's negative impact on the Indian monsoon.
IMD's forecasting models incorporate both ENSO state and IOD, along with North Atlantic SSTs and Eurasian snow cover as predictors.

Connection to this news: The IMD's second-stage downgrade is directly linked to the rising probability of El Niño development (82% by June, 90%+ during July–August). The timing is critical — peak monsoon months (July–August) coinciding with peak El Niño probability creates a high-risk window for rainfall deficiency.

Drought Classification and Impact on Agriculture and Food Security

India classifies drought under the Drought Management Manual (National Disaster Management Authority) by two criteria: meteorological drought (rainfall deficit) and agricultural drought (soil moisture and crop stress). Meteorological drought at national level: rainfall below 75% of LPA (moderate drought) and below 50% (severe drought). At sub-divisional level, below-normal rainfall for three or more consecutive weeks triggers an agricultural drought watch.

The 2026 below-normal forecast primarily threatens kharif crops: rice, pulses (tur, moong, urad), oilseeds (groundnut, soybean), sugarcane, and cotton — all heavily dependent on June–September rainfall.
India's kharif food grain production accounts for approximately 50% of annual food grain output.
Agricultural drought risks cascading effects: lower kharif output → higher food prices → rural distress → reduced rural consumption → macroeconomic slowdown.
Reservoir storage (managed by the Central Water Commission, CWC) is the key buffer: below-normal monsoon filling of reservoirs impacts rabi (winter) crop irrigation, power generation, and drinking water supply.
National Food Security Act, 2013 (NFSA): Ensures subsidised grain to ~80 crore beneficiaries — the PDS buffer-stock mechanism is the government's primary tool to manage food inflation in drought years.
Minimum Support Price (MSP) revisions in drought years are a policy tool to protect farmer incomes even when yields fall.

Connection to this news: IMD's downward revision shifts the 2026 monsoon risk from "cautionary" to "action-triggering" — government agencies (Ministry of Agriculture, CWC, NDMA, state governments) are expected to activate drought preparedness protocols, including buffer stock assessment, crop insurance activation under PMFBY, and water-sharing coordination across river basins.

IMD — Forecasting Methodology and Institutional Role

The India Meteorological Department (IMD), established in 1875, is under the Ministry of Earth Sciences. It is India's national meteorological service responsible for weather forecasting, seismology, and climate monitoring. The Long Range Forecast (LRF) for the Southwest Monsoon uses a combination of dynamical models (NWP — Numerical Weather Prediction, including the coupled Global Forecast System and ECMWF models) and statistical models, integrated through an ensemble approach since 2021.

IMD's monsoon forecast uses predictors including: ENSO indices (Niño 3.4 SST), IOD, Eurasian snow cover, North Atlantic SST anomalies, and seasonal pressure patterns.
Two-stage forecast strategy: Stage 1 (April) — seasonal forecast; Stage 2 (late May) — updated outlook incorporating May ENSO data.
IMD also issues 5-day, weekly, and monthly outlooks; extended range forecasts (10–30 days) are provided through the IITM ERPAS system.
IMD's forecast accuracy for the national seasonal total has improved significantly — but regional and sub-seasonal forecasts remain a challenge.
The 2021 modification to the forecasting strategy incorporated dynamical coupled ocean-atmosphere models as the primary tool, with statistical models serving as guidance — aligning India with international best practice.

Connection to this news: The second-stage downgrade in late May (the Stage 2 window) reflects exactly the design of India's two-stage system — incorporating the latest ENSO data (late-May Pacific SST readings) that were not available when the April Stage 1 forecast was issued.

Key Facts & Data

2026 monsoon forecast (Stage 2): 90% of LPA (model error ±4%) — "below normal."
April 2026 forecast (Stage 1): 92% of LPA.
LPA definition: Average rainfall over India during June–September (1971–2020 base period) = approximately 868.6 mm.
IMD rainfall categories: Above Normal ≥110%; Normal 96–110%; Below Normal 90–95%; Deficient <90% of LPA.
El Niño probability: 82% by June 2026; >90% during July–August 2026.
Last below-normal monsoon: 2023 (94% of LPA) — also an El Niño year.
Monsoon core zone: Most rain-fed agricultural land; forecast below 94% of LPA in 2026.
ENSO Niño 3.4 threshold: +0.5°C above normal SST for 5 consecutive overlapping 3-month periods = El Niño.
IMD established: 1875; under Ministry of Earth Sciences.
Two-stage LRF: Stage 1 in April; Stage 2 in late May.
PMFBY (Pradhan Mantri Fasal Bima Yojana): Primary crop insurance scheme activated during drought.
National Food Security Act, 2013: Covers ~80 crore beneficiaries through subsidised PDS grain.
Central Water Commission (CWC): Monitors reservoir storage levels; key drought early-warning institution.
IOD (Indian Ocean Dipole): Positive IOD can partially offset El Niño's negative effect on Indian monsoon.