The India Meteorological Department (IMD) has forecast that the southwest monsoon will advance into Kerala on May 26, 2026 — six days earlier than the standard onset date of June 1. This follows the 2025 monsoon, which arrived on May 24 — the earliest onset since 2009. While an early arrival date is often interpreted as a positive agricultural signal, the IMD and other weather agencies have simultaneously warned of “below normal” rainfall for the season due to the likely development of an El Niño event in the central equatorial Pacific — a periodic warming phenomenon that has historically suppressed Indian monsoon rainfall. This combination of early onset and below-normal total rainfall exemplifies a critical scientific distinction that every UPSC aspirant must understand: the date of monsoon onset does not correlate with the quantum of seasonal rainfall.
For India, where agriculture directly employs approximately 42% of the workforce and contributes nearly 18% of GDP, the southwest monsoon is not merely a meteorological event — it is a macroeconomic and food security phenomenon of the first order. The monsoon provides approximately 75% of India’s annual rainfall and is decisive for the kharif crop season (June-September), which produces rice, maize, pulses, and oilseeds. A below-normal monsoon year directly threatens food inflation, rural income, and agricultural GDP — all of which have cascading effects on the broader economy, government welfare spending, and RBI monetary policy.
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The IMD’s increasing forecasting precision, enabled by supercomputing capacity and advances in meteorological modelling, is itself a significant achievement of India’s science and technology apparatus — one that UPSC aspirants should appreciate both for its technical dimensions and its governance implications.
Background and Context: India’s Monsoon System and IMD’s Forecasting Framework
Five Important Key Points
- The southwest monsoon’s onset over Kerala is declared by the IMD based on a multi-criteria framework requiring a prescribed quantity of rainfall across a minimum number of meteorological stations in Kerala and parts of Karnataka, combined with specific wind speed and cloud density thresholds — making it a scientifically rigorous rather than arbitrary determination.
- El Niño, defined as a periodic warming of the central equatorial Pacific Ocean surface temperature by 0.5°C or more, suppresses Indian monsoon rainfall by altering global atmospheric circulation patterns, including the Walker Circulation that drives moisture transport toward the Indian subcontinent.
- The IMD has a historical record of forecasting below-normal rainfall in El Niño years: in 2015, the IMD warned of “near normal” rainfall at 96% of the Long Period Average (LPA) but actual rainfall was only 86% of LPA — illustrating the persistent challenge of quantitative monsoon forecasting.
- India’s monsoon forecasting infrastructure has been significantly upgraded with the installation of Pratyush and Mihir supercomputers (total processing capacity exceeding 6.8 petaflops) and the deployment of Doppler Weather Radars across the country, substantially improving 5-7 day forecast accuracy.
- The Ministry of Earth Sciences (MoES), of which IMD is a constituent organisation, published its Earth System Science Vision document outlining India’s 10-year roadmap for improving weather and climate forecasting — including the planned installation of additional monitoring stations and integration of satellite data from INSAT-3DS launched in February 2024.
The Science of El Niño and Indian Monsoon Variability
El Niño–Southern Oscillation (ENSO) is the primary driver of year-to-year variability in the Indian southwest monsoon. During El Niño years, the sea surface temperature in the central and eastern equatorial Pacific rises above normal, weakening the Walker Circulation and reducing the moisture influx into the Indian subcontinent. Historical data shows that approximately 60% of strong El Niño years are associated with below-normal Indian monsoon rainfall (defined as rainfall below 90% of the LPA of 87 cm). However, the relationship is not deterministic — the Indian Ocean Dipole (IOD), Madden-Julian Oscillation (MJO), and Eurasian snow cover also modulate monsoon variability, sometimes counteracting El Niño’s suppressive influence.
The La Niña phase — opposite of El Niño — generally corresponds to above-normal Indian monsoon rainfall. The 2022 and 2023 monsoons were influenced by La Niña and El Niño respectively, contributing to inter-annual rainfall variability that challenges agricultural planning.
IMD’s Institutional Framework and India’s Weather Science Architecture
The India Meteorological Department, established in 1875, functions under the Ministry of Earth Sciences (MoES). Its four-stage long-range monsoon forecast — issued in April, May, and updated in June and July — uses a suite of dynamical and statistical models. The April forecast provides an initial estimate; the June update, issued after the monsoon has actually established over the peninsula, has historically been the most reliable. The IMD uses a 5-category probability forecast framework rather than a single deterministic prediction, reflecting the inherent uncertainty of seasonal forecasting.
INSAT-3DS, India’s newest weather satellite launched in February 2024, carries advanced multispectral imagers and sounders that significantly enhance cloud cover monitoring and atmospheric temperature/humidity profiling over the Indian Ocean — critical for monsoon prediction.
Agricultural and Economic Implications
A below-normal monsoon has differential impacts across India’s agriculture: rain-fed areas (approximately 55% of net sown area) are most vulnerable, while canal-irrigated and groundwater-dependent areas have greater resilience. The kharif crops most vulnerable to monsoon deficit are pulses, coarse cereals, and oilseeds — the commodities whose price inflation most directly impacts BPL households. Rice, though also kharif-dependent, benefits from irrigation infrastructure in major producing states.
Food inflation, already elevated due to the West Asia war’s impact on supply chains and fuel costs, would be further amplified by a monsoon deficit. The RBI, in its monetary policy deliberations, explicitly models monsoon forecasts as a key risk factor for the inflation outlook. A below-normal monsoon year would likely require additional government fiscal support — through the Pradhan Mantri Fasal Bima Yojana (PMFBY), price support mechanisms, and enhanced food grain distribution — adding pressure to the fiscal deficit.
Bihar Connection: Bihar is acutely sensitive to monsoon performance. The state receives nearly 80% of its annual rainfall from the southwest monsoon (June-September). Bihar’s flood plains — particularly in North Bihar along the Gandak, Bagmati, Kosi, and Mahananda rivers — are paradoxically vulnerable to both flood (excess rainfall) and drought (deficient rainfall) in different parts of the state. Below-normal monsoon years mean deficient rainfall in South Bihar and Jharkhand border districts, devastating kharif crops and rural incomes. The Kosi river’s catchment extends into Nepal, and monsoon variability also modulates the flood risk that threatens millions of people in North Bihar annually. Bihar’s agricultural economy, which still employs the majority of the state’s workforce, is therefore directly and deeply affected by every monsoon forecast.
Way Forward
India should invest in district-level agrometeorological advisory services that translate IMD’s seasonal forecasts into actionable recommendations for farmers regarding crop variety selection, sowing dates, and input management. The PMFBY should be reformed to ensure faster claims settlement and deeper penetration in deficient rainfall zones. Expanding micro-irrigation — drip and sprinkler systems — can significantly reduce crop water requirements and buffer against monsoon variability. Increasing reservoir storage capacity and groundwater recharge through watershed development can provide insurance against rainfall deficits. Greater integration of IMD forecasts into government procurement and buffer stock planning would reduce food price volatility in below-normal monsoon years.
Relevance for UPSC and SSC Examinations
UPSC: GS-I (Geography — Indian monsoon system, ENSO, climate variability); GS-III (Indian economy — agriculture, food security, inflation management, disaster management); Science and Technology (IMD forecasting, INSAT-3DS, supercomputing). SSC: General Awareness (monsoon system, El Niño, IMD, kharif crops, PMFBY). Key terms: El Niño, ENSO, Indian Ocean Dipole, Walker Circulation, Long Period Average, Pratyush supercomputer, INSAT-3DS, PMFBY, Kharif season, IMD onset criteria.