Climate of India and Monsoon Mechanism

Factors Influencing India's Climate

India's climate is shaped by a complex interplay of geographical location, topography, and atmospheric circulation patterns. Despite lying largely in the tropical belt, India experiences a wide variety of climatic conditions.

Key Controlling Factors

The Monsoon Mechanism

The Indian monsoon is a large-scale seasonal wind system driven by differential heating of land and sea, modulated by upper-air circulation patterns and oceanic conditions.

Classical Theory vs. Modern Understanding

Remember: The Indian monsoon is NOT simply caused by "differential heating of land and sea" — that is the classical (thermal) theory, which is incomplete. The modern explanation involves the seasonal shift of the ITCZ, the role of the Tropical Easterly Jet and Subtropical Westerly Jet, the Tibetan Plateau as an elevated heat source, and the Somali Jet. UPSC Mains expects you to go beyond the textbook thermal theory and discuss the dynamic factors.

Inter-Tropical Convergence Zone (ITCZ)

The ITCZ is a low-pressure belt that shifts seasonally. During the Indian summer, it migrates northward to approximately 20-25 degrees N over the Ganga Plain. This northward shift draws in moisture-laden trade winds from the southern hemisphere, which, after crossing the Equator, turn right (Coriolis effect) and arrive over India as the southwest monsoon.

Key Atmospheric Features

El Nino, La Nina, and IOD

These oceanic-atmospheric phenomena significantly modulate monsoon rainfall from year to year.

El Nino and La Nina (ENSO)

Indian Ocean Dipole (IOD)

Common Mistake: Students often confuse IOD with ENSO. The IOD operates in the Indian Ocean (SST difference between western and eastern Indian Ocean), while ENSO operates in the Pacific Ocean (SST anomaly in central/eastern Pacific). A 2017 Prelims question tested exactly this — Statement 1 wrongly paired IOD with the "Eastern Pacific Ocean" and many aspirants marked it correct. Always remember: IOD = Indian Ocean only.

Recent ENSO and IOD Examples

Interplay of ENSO and IOD

Seasons of India

India experiences four distinct seasons, primarily governed by the monsoon cycle.

The Four Seasons

Pre-Monsoon Rainfall Phenomena

Exam Tip: Pre-monsoon phenomena are a Prelims favourite. Remember that Mango Showers (Kerala/Karnataka), Nor'westers/Kalbaisakhi (West Bengal/Assam), and Cherry Blossoms (Karnataka coffee areas) are all PRE-monsoon events occurring in March-May. Do not confuse them with the actual southwest monsoon which arrives in June. Also note: Loo is a hot dry wind (not rain), while the others bring rainfall.

IMD Monsoon Onset & Withdrawal — Normal Dates

The Southwest Monsoon advances from south to north and west; the Northeast (retreating) monsoon withdraws in reverse.

Mnemonic — SW Monsoon advances 1 June → 15 July (north-west tip); withdraws 17 September → 15 October. The 1 June onset over Kerala and 17 September withdrawal from north-west India are the two most-tested IMD dates.

Two Branches of the Southwest Monsoon

Why does Tamil Nadu get most of its rain in October–December (Northeast / Retreating Monsoon)? The Coromandel coast lies on the leeward side of the Western Ghats during the SW monsoon (June–September), and the Bay of Bengal branch crosses overland before reaching it. When the monsoon retreats, north-easterly winds pick up moisture from the warm Bay of Bengal and dump it as the NE monsoon on the Tamil Nadu coast (~75% of Chennai's annual rainfall comes in this period).

Western Disturbances

Western Disturbances (WDs) are extratropical cyclonic systems originating over the Mediterranean Sea, Black Sea, and Caspian Sea. They travel eastward, steered by the subtropical westerly jet stream, and bring winter and post-monsoon precipitation to northwestern India.

IMD Monsoon Forecasting

The India Meteorological Department (IMD) uses a combination of statistical and dynamical models for seasonal monsoon prediction.

Rainfall Distribution in India

India's average annual rainfall is approximately 119 cm, but it is extremely unevenly distributed.

Rainfall Zones

Rainfall Variability

Record Rainfall Stations

Koppen Climate Classification of India

India spans multiple Koppen climate zones due to its varied topography and latitude.

Climate Change Impact on India

Observed Changes

Projected Impacts

Important for UPSC

Prelims Focus

• Onset and withdrawal dates of monsoon (Kerala: 1 June onset; NW India withdrawal: 17 September)
• Difference between El Nino, La Nina, and IOD
• Koppen climate classification codes for Indian regions
• Matching rainfall zones with regions
• Pre-monsoon phenomena (Mango Showers, Nor'westers, Loo)
• Jet streams and their role in monsoon mechanism
• Record rainfall stations
• Western Disturbances -- origin, season, and affected regions

Mains Dimensions

• Critically examine the role of ENSO and IOD in monsoon variability (GS1)
• Impact of climate change on Indian monsoon and its implications for agriculture (GS1/GS3)
• Western Disturbances and their increasing role in winter rainfall (GS1)
• Changing cyclone patterns in Arabian Sea and Bay of Bengal (GS1/GS3)
• Adaptation and mitigation strategies for climate change in India (GS3)
• Evaluate IMD's monsoon forecasting capabilities -- dynamical vs statistical models (GS1/GS3)

Interview Angles

• Is the Indian monsoon becoming more unpredictable? What are the implications?
• How would a weakening monsoon affect India's food security?
• Can India's monsoon forecasting capability be improved? What role does IMD play?
• Discuss the concept of "monsoon breaks" and their impact on agriculture.

Vocabulary

Monsoon

• Pronunciation: /mɒnˈsuːn/
• Definition: A seasonal reversal of wind direction associated with large-scale changes in atmospheric pressure, bringing prolonged wet and dry seasons to tropical and subtropical regions.
• Root: Arabic mawsim (موسم) = season; from wasama = to mark, brand; via Portuguese monção and Dutch moesson
• Origin: From Portuguese monção and Dutch moesson, derived from Arabic mawsim (موسم) meaning "season," ultimately from wasama ("to mark, to brand"); first recorded in English in 1584.
• Part of Speech: noun
• Word Family: monsoon (n), monsoonal (adj), monsoons (n pl), pre-monsoon (adj), post-monsoon (adj)
• Usage: The economy's enduring dependence on a timely and well-distributed monsoon underscores the urgency of climate-resilient agriculture, since a single deficient rainfall season can derail rural incomes, stoke food inflation and widen fiscal stress.
• Synonyms: seasonal wind, rains, rainy season, trade wind, downpour, deluge
• Antonyms: drought, dry season, aridity
• Mnemonic: From Arabic mawsim, "season" — picture the MONSOON arriving like clockwork each SEASON; "MON-SOON" = the rains come "soon" every year.

Cyclone

• Pronunciation: /ˈsaɪkləʊn/
• Definition: A large-scale atmospheric system of winds rotating around a centre of low pressure — anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
• Root: Coined 1848 by H. Piddington from Greek kyklos = circle, wheel; cf. kyklōma = coil
• Origin: Coined by British meteorologist Henry Piddington in the 1840s, derived from Greek kyklos ("circle") or kyklōma ("wheel, coil of a snake"); first published use dates to 1848.
• Part of Speech: noun
• Word Family: cyclonic (adj), cyclonically (adv), anticyclone (n), anticyclonic (adj), cyclogenesis (n)
• Usage: As coastal cyclones grow more frequent and ferocious under a warming climate, India's disaster-management apparatus must pivot from reactive relief to anticipatory resilience, embedding early-warning systems and cyclone-resistant infrastructure into the developmental fabric of its eastern seaboard.
• Synonyms: hurricane, typhoon, tempest, whirlwind, storm, tornado
• Antonyms: anticyclone, calm, lull
• Mnemonic: CYCLE + -one: a cyclone makes winds CYCLE in a giant circle, just as its Greek root kyklos means 'circle'.

Isotherm

• Pronunciation: /ˈaɪsəʊˌθɜːm/
• Definition: A line drawn on a map or chart connecting points that have the same temperature at a given time or the same mean temperature over a given period.
• Root: Greek isos = equal; thermē = warmth, heat; coined by Humboldt, 1817 via French isotherme
• Origin: From French isotherme, coined by Alexander von Humboldt in 1817, combining Greek isos ("equal") and thermē ("warmth, heat").

• Part of Speech: noun
• Word Family: isothermal (adj), isothermally (adv), isothermics (n)
• Usage: In mapping the country's deepening climate stress, planners increasingly rely on shifting isotherms, whose poleward and altitudinal migration signals the encroachment of heat-stressed zones onto once-temperate agricultural belts.
• Synonyms: isothermal line, temperature contour, isopleth, isoline, contour line
• Mnemonic: ISO = "equal" + THERM = "heat" (as in thermometer/thermal): an isotherm joins places of equal heat, i.e. the same temperature.

Key Terms

Köppen Climate Classification

• Definition: The Köppen Climate Classification is an empirical system that divides the world's climates into five major groups (A–E) and numerous sub-types, using long-term monthly averages of temperature and precipitation, on the assumption that native vegetation is the best expression of climate.
• Context: Devised by the German-Russian climatologist Wladimir Köppen, who published a first version in 1884 and a quantitative scheme around 1900, it was refined by Köppen himself (notably 1918 and 1936) and later by Rudolf Geiger, giving the widely cited "Köppen–Geiger" system. It remains the most widely used climate classification in education and research because it is simple, vegetation-linked, and mappable globally. Glenn Trewartha later modified it (1966/1980) to give finer resolution to mid-latitude climates.
• UPSC Relevance: This is a foundational GS1 (Geography) concept that underpins questions on world climatic regions, Indian climate, and biome-climate linkages; it is most often tested in Prelims through matching climate codes (e.g., Aw, BWh, Cwg) to regions or describing characteristic vegetation. In Mains GS1 it supports answers on climatic regions of India, monsoon, and contrasts with rival schemes (Thornthwaite, Trewartha). No verified PYQ is cited for this exact term; treat it as enabling knowledge for the broader "climatology and regional geography" topic family.

Bhabar and Terai

• Definition: Bhabar and Terai are two of the four parallel relief belts of India's Northern Plains, lying along the Himalayan foothills: the Bhabar is a narrow, porous, pebble-strewn piedmont strip where rivers vanish underground, and the Terai is the marshy, ill-drained, forested belt just south of it where those streams re-emerge at the surface.
• Context: As rivers descend from the Himalayas onto the plains, they lose energy and dump their coarsest load, building merging alluvial fans that form the Bhabar. Because this belt is highly porous, the streams sink and flow underground, leaving dry river courses; they resurface a little further south in the Terai, producing a wet, swampy, densely vegetated zone. Together with the older Bhangar and newer Khadar alluvium further south, Bhabar and Terai make up the north-to-south sequence of the Indo-Gangetic-Brahmaputra plain (NCERT Class 9, Physical Features of India).
• UPSC Relevance: This is a foundational physical-geography concept that underpins UPSC questions on the Northern Plains, river behaviour, soil and the Indo-Gangetic plain. Prelims frequently tests the porosity-driven disappearance of Bhabar streams and their re-emergence in the Terai, plus the difference between Bhabar/Terai (relief-based) and Bhangar/Khadar (age-of-alluvium based). For Mains GS1 (physiography) and GS3 (ecology, agriculture, conservation), the Terai connects to the Terai Arc Landscape, tiger reserves such as Jim Corbett and Dudhwa, and grassland conservation.

Loo (Hot Wind)

• Definition: The Loo is a strong, hot, dry, dusty westerly wind that blows across the northern plains of India and Pakistan during the pre-monsoon summer months (chiefly May and June), with afternoon temperatures often reaching 45-50°C. It is classified as a local wind, generated by intense surface heating over the Thar Desert and the Indo-Gangetic Plain.
• Context: During May and June the near-vertical sun heats the north-western desert and plains intensely, creating a low-pressure zone into which dry, super-heated air rushes from the west, forming the Loo. It blows mainly in the afternoon and may persist into the evening, scorching vegetation and posing serious heatstroke risk. The Loo is a hallmark of India's "hot weather season" and weakens only with the onset of the south-west monsoon, which brings moisture and cooler air.
• UPSC Relevance: This is a foundational physical-geography concept that underpins Prelims and Mains questions on India's climate, local/regional winds, the pre-monsoon season, and heat-wave hazards. In Prelims, UPSC tests it as a factual local-wind identification item (often paired with other Indian local winds such as the andhi dust storms of the north-west and the Nor'westers/Kalbaisakhi of eastern India). In Mains GS1 (physical geography) and GS3 (disaster management), it connects to heat-wave vulnerability, the India Meteorological Department's heat-wave criteria, and climate-change-driven extreme-heat events. No verified PYQ exists for this exact term, so it is best mastered as part of the broader "Indian climate and local winds" topic family.

Isohyet

• Definition: An isohyet is a line on a map joining places that receive equal amounts of rainfall (precipitation) over a stated period or during a particular storm. The name comes from the Greek "iso" (equal) and "hyetos" (rain).
• Context: Isohyets are a type of isoline (like isotherms for temperature and isobars for pressure) used widely in meteorology, climatology and hydrology to visualise the spatial distribution of rainfall. A map covered with such lines is called an isohyetal map, and the value attached to each line is read in millimetres or centimetres. In India, isohyetal maps reveal the sharp contrast between the heavy-rainfall windward slopes of the Western Ghats and North-East and the arid Thar region of western Rajasthan.
• UPSC Relevance: Isohyet is a foundational physical-geography concept that underpins Prelims questions on isolines and on the distribution of Indian monsoon rainfall, where candidates are expected to distinguish isohyet (rainfall) from isotherm (temperature), isobar (pressure) and isohaline (salinity). In Mains GS1 (physical and Indian geography), the idea supports answers on monsoon mechanism, rain-shadow regions, drought-mapping and water-resource planning. No direct PYQ is cited for the exact term, but it is a recurring building block for questions on rainfall variability and climatic regions of India.

Western Disturbances

• Definition: Western Disturbances are extratropical (non-monsoonal) low-pressure storm systems that originate over the Mediterranean, Caspian and Black Sea region and are steered eastward by the subtropical westerly jet stream to bring winter and pre-monsoon rain, snow, fog and hail to north-western India and the western Himalayas.
• Context: Unlike the monsoon, which draws moisture from the Indian Ocean and flows in from the south-west, Western Disturbances (WDs) are upper-air systems embedded in the mid-latitude westerlies, travelling across West Asia, Iran, Afghanistan and Pakistan before reaching the subcontinent. On average four to five WDs cross north-west India during the winter (December–February), supplying most of the season's rainfall and the Himalayan snowpack that feeds rivers such as the Indus and Ganga. This precipitation is critical for rabi crops, especially wheat. Recent peer-reviewed research (Weather and Climate Dynamics, 2024) shows their frequency and seasonality are shifting under climate change.
• UPSC Relevance: Western Disturbances are a foundational GS1 physical-geography concept that underpins UPSC questions on India's climate, the winter season ("mahawat" rains), and the contrast between monsoonal and extratropical precipitation. Prelims commonly tests the source region (Mediterranean, not Indian Ocean), the steering mechanism (subtropical westerly jet stream), and which crops/seasons benefit. Mains (GS1 and GS3) links WDs to rabi-crop agriculture, Himalayan snowfall and water security, and increasingly to climate-change-driven extreme events such as cloudbursts and unseasonal hail. No verified PYQ exists for this exact term, but it is a recurring sub-theme within Indian climatology and disaster-management questions.

ITCZ (Inter-Tropical Convergence Zone)

• Pronunciation: /ˌɪntəˈtrɒpɪkəl kənˈvɜːdʒəns zəʊn/ (abbreviated colloquially as "the itch," /ɪtʃ/)
• Definition: A thermal low-pressure belt encircling the Earth near the equator where the northeast and southeast trade winds converge, producing vigorous uplift, heavy cloudiness, frequent thunderstorms, and intense convectional rainfall. It migrates seasonally — shifting northward to approximately 20-25 degrees N over the Indo-Gangetic Plain during the Northern Hemisphere summer (June-July), where it is called the "monsoon trough," and retreating southward to around 15 degrees S during December-January. This seasonal migration is the primary driver of the Indian southwest monsoon.
• Context: The zone was historically known to sailors as the "doldrums" due to its calm, windless conditions that becalmed sailing ships. The concept was formally identified and named as the ITCZ as global atmospheric circulation patterns were mapped in the early 20th century. When the ITCZ shifts northward over India in summer, the southeast trade winds of the Southern Hemisphere cross the equator, are deflected rightward by the Coriolis force, and arrive over India as the moisture-laden southwest monsoon winds. The position and intensity of the ITCZ directly determine the distribution and variability of monsoon rainfall across India.
• UPSC Relevance: GS1 Geography. Prelims tests the ITCZ's role in monsoon onset, its seasonal migration to 20-25 degrees N over the Ganga Plain, and its alternate name "monsoon trough." Mains expects detailed explanation of how ITCZ shift drives the southwest monsoon mechanism, going beyond the classical thermal theory to include jet stream dynamics (STJ withdrawal, TEJ establishment), Somali Jet (cross-equatorial low-level jet), Mascarene High, and Tibetan Plateau heating as an elevated heat source. A foundational concept for any monsoon-related answer.

El Nino Southern Oscillation (ENSO)

• Pronunciation: /ɛl ˈniːnjəʊ ˈsʌðən ˌɒsɪˈleɪʃən/
• Definition: A coupled ocean-atmosphere climate phenomenon in the tropical Pacific Ocean that oscillates between three phases — El Nino (anomalous warming of central/eastern Pacific SSTs, weakening the Walker Circulation), La Nina (anomalous cooling, strengthening the Walker Circulation), and Neutral — significantly influencing global weather patterns including the Indian monsoon. El Nino events tend to suppress Indian monsoon rainfall (~60% of El Nino years see deficit rainfall), while La Nina years tend to bring normal-to-excess monsoon rainfall.
• Context: Peruvian fishermen named the warm coastal current El Nino de Navidad ("The Christ Child") because it was most noticeable around Christmas; the earliest recorded use in a climate context dates to 1892 (Captain Camilo Carrillo). Sir Gilbert Walker identified the "Southern Oscillation" in atmospheric pressure in the early 20th century, and Jacob Bjerknes linked the oceanic and atmospheric phenomena in the late 1960s. As of May 2026, ENSO is in rapid transition to El Niño — NOAA/IRI report ~82–98% probability of El Niño in the May–July 2026 window, with the event expected to persist through December 2026–February 2027. This directly drove IMD's 2026 Long Range Forecast (April 13, 2026): 92% of LPA (below-normal) — India's first below-normal monsoon forecast in three years. IMD cites a possible late positive IOD development (late-season) that may offer partial offset, but the El Niño-dominant signal is the primary driver.
• UPSC Relevance: GS1 Geography and GS3 Agriculture. Prelims 2017 tested the distinction between ENSO (Pacific Ocean) and IOD (Indian Ocean) — a common trap. Mains regularly asks to "critically examine the role of ENSO and IOD in monsoon variability." Focus on: El Nino causing deficit rainfall, La Nina enhancing rainfall, positive IOD offsetting El Nino's negative impact (as in 2019 when the strongest positive IOD on record countered an El Nino Modoki to produce 110% of LPA rainfall). Remember the four ENSO-IOD combinations and their likely monsoon outcomes for Mains answers.

Cross-paper relevance

• GS1 — Geography (primary) — India's climatic regions, monsoon onset/retreat, Western Disturbances, North-East Monsoon, climatic diversity
• GS3 — Agriculture: monsoon-dependent kharif crops; IMD seasonal forecasting; drought and flood cycles; climate change impact on monsoon variability
• GS3 — Disaster management — Cyclone preparedness on east coast (Bay of Bengal cyclone frequency); flood management in Assam and Bihar; heat wave action plans
• Essay — "India's agricultural calendar is a hostage to the monsoon — is it time to change?" (recurring)

Recent Developments (2024–2026)

2024 Southwest Monsoon — Above-Normal with Record Extremes

India's 2024 Southwest Monsoon (June–September) delivered 934.8 mm of rainfall — 108% of the Long Period Average (LPA) of 868.6 mm (1971–2020 base period). Distribution was uneven: Central India received 119% of LPA, South Peninsula 114%, Northwest India 107%, but Northeast India only 86%. India recorded 2,632 instances of very-heavy rainfall and 473 instances of extremely-heavy rainfall — the highest frequency in five years. Despite an initial El Niño condition, the transition to La Niña and a positive Indian Ocean Dipole supported above-normal rainfall. The 2024 monsoon also brought catastrophic events: the Wayanad landslides (254 confirmed + 118 missing/presumed dead, ~372 total), Kerala floods, Assam floods (affecting 400,000 people), and Vijayawada floods (Krishna River breach).

UPSC angle: IMD forecasting, rainfall distribution, ENSO-IOD interactions, and the increasing frequency of extreme monsoon events due to climate change are core GS1 topics.

2025 Monsoon — Second Consecutive Above-Normal Season, Record Disaster Intensity

India's 2025 SW Monsoon (June–September) delivered 937.2 mm — 108% of LPA, making it the second consecutive above-normal year. Key features (IMD Final Monsoon Report, December 2025):

• Earliest-ever onset over Kerala: May 24, 2025 (vs. normal June 1); Mumbai reached in just 2 days — fastest advance in recorded history
• Northwest India: 127% of LPA — 6th highest since 1901; highest since 2001
• East & Northeast India: 80% of LPA — the only deficient zone; Arunachal Pradesh, Assam-Meghalaya, Bihar all below-normal
• Annual all-India rainfall 2025: 110% of LPA (1,274 mm) — WMO Statement on Climate of India 2025 (January 2026); May 2025 pre-monsoon was the highest on record since 1901 (142% of LPA for pre-monsoon season)

Disaster dimension: India recorded climate-driven disasters on 331 of 334 days in 2025 (Down to Earth, year-end 2025) — vs. 295 in 2024. Season-wide flood/landslide deaths exceeded 1,500; Andhra Pradesh (608), Madhya Pradesh (537), and Jharkhand (478) were worst-affected states. Maharashtra had the largest cropland damage (8.4 million hectares). The above-normal rainfall aggregate masked severe intra-season volatility — by August, 19% of the country was in drought or drought-like conditions despite the early surplus, illustrating how "above-normal total" can co-exist with devastating localised deficits.

UPSC angle: The 2025 monsoon is highly exam-relevant for Mains 2026 — the "distribution paradox" (above-normal total + regional deficits + 1,500+ deaths) is a ready case study for questions on climate adaptation, early warning systems, and food security under monsoon variability. The May 24 onset date tests understanding of monsoon triggers (ITCZ + Somali Jet + SST anomaly).

2025 North Indian Ocean Cyclone Season — First Named Storm in Arabian Sea; Record Disaster Count

The 2025 North Indian Ocean cyclone season was described as one of the most active and costliest on record. Key developments:

• Cyclone Shakti (1–7 October 2025): The first named cyclonic storm of the season, forming from a well-marked low-pressure area over the northeast Arabian Sea on 30 September 2025; upgraded to cyclonic storm "Shakhti" on 3 October. Intensified into a severe cyclonic storm (winds ~120–130 km/h). Moved west-southwestward toward Oman and did not make landfall on India's coast, but triggered orange and yellow alerts for six Maharashtra coastal districts (Mumbai, Thane, Palghar, Raigad, Ratnagiri, Sindhudurg) from October 3–7; rough-to-very-rough seas (waves 3–4 m) affected the north Maharashtra coast. (Source: IMD IMD NIO Cyclone Bulletin; IIRS/ISRO Sudoor Manthan analysis, October 2025.)

• Late-season Bay of Bengal activity (October 2025): IMD warned of a deep depression over the southeast Bay of Bengal intensifying into a severe cyclonic storm expected to make landfall between Machilipatnam and Kalingapatnam (around Kakinada) on October 28, 2025, affecting coastal Andhra Pradesh.

• Overall season context: India recorded climate-driven disasters on 331 of 334 days in 2025 (Down to Earth, year-end 2025), with floods, cyclones, and extreme rainfall events contributing to over 1,500 deaths from weather extremes during the 2025 monsoon and post-monsoon period.

UPSC angle (Prelims 2027 / Mains 2026): The 2025 cyclone season is exam-relevant for three reasons: (1) Shakti's Arabian Sea formation versus the more common Bay of Bengal origin illustrates the increasing frequency of Arabian Sea cyclones linked to rising SSTs; (2) the late-October Bay of Bengal system reinforces the concept of peak cyclone frequency in October–November on India's east coast; (3) the broader "331 of 334 days of disasters" statistic is a powerful Mains hook for climate adaptation and resilience questions.

IMD 2026 Monsoon Forecast — Below-Normal / Deficient Risk (Updated June 2026)

First forecast (April 13, 2026): IMD's Long Range Forecast: 92% of LPA — below-normal. India's first below-normal forecast in three years. El Niño cited as primary driver.

Updated forecast (May 29, 2026): IMD revised its forecast downward to 90% of LPA (PIB, PRID 2266479). Key figures:

Why revised downward: El Niño strengthened faster than expected through May 2026; warm Equatorial Pacific SSTs confirmed; NOAA/IRI June 2026 outlook shows El Niño persisting through December 2026–February 2027. IOD (Indian Ocean Dipole) remains neutral — the hoped-for positive IOD offset has not materialised.

Spatial distribution (June 2026 outlook): Below-normal rainfall most likely over most parts of India except parts of Northwest India, Northeast India, and Eastern South Peninsula — where normal to above-normal rainfall is likely.

June 2026 specific forecast: Average rainfall for June 2026 most likely below normal (<92% of LPA); core agricultural zone (monsoon core zone — central, western, eastern India) also expected below normal (<94% of LPA); above-normal heat waves possible where rainfall is deficient.

Policy implications (UPSC GS3 angle):

• Kharif 2026-27: Below-normal monsoon → reduced sowing of moisture-sensitive crops (pulses, oilseeds) in rainfed areas; paddy sowing may shift toward irrigated zones
• Food inflation: Inadequate monsoon → reduced agricultural output → food price pressure; RBI MPC will need to factor monsoon outcomes into inflation projections
• MGNREGS drought protocol: Below-normal rainfall in >25% of districts triggers enhanced MGNREGS allocations (Drought Management Framework)
• Reservoir levels: India's 150 major reservoirs at 28% of capacity (early June 2026 vs 32% for 10-year average for this date) — reduced hydro power generation likely

UPSC angle (Prelims 2027): LPA = 868.6 mm (1971–2020 base period). Categories: Normal = 96–104% of LPA; Below-normal = 90–96%; Deficient = <90%; Excess = >110%. 2026 revised forecast = 90% of LPA; 60% probability of deficient season; 84% probability of below-normal or deficient — the most pessimistic monsoon outlook since 2023. IMD issues two LRF bulletins: April (first) and late May/June (updated). El Niño = ENSO warm phase → typically reduces Indian monsoon rainfall.

Current Affairs Connect

Sources: IMD -- Monsoon FAQ | MoES -- El Nino Effect on Monsoon | PIB -- India's Energy Landscape (climate data) | NCERT -- Climates of India