Topic 11: Seasons, Climatic Divisions, Droughts & Floods

The monsoon gives India its rhythm; this chapter reads that rhythm season by season and maps its hazards. It walks the four seasons — cold winter (with western disturbances & mahawat rain), the hot pre-monsoon (with the loo and local storms like the kalbaisakhi/nor'westers, mango & blossom showers), the rainy south-west monsoon, and the retreating (NE) monsoon — then classifies India's climate using the Koppen (and Stamp/Trewartha) schemes. It closes with India's two great climatic hazards: droughts (types, drought-prone areas, DPAP/DDP) and floods (river, flash, urban & coastal; cross-border flood management), set inside the national disaster-management framework (NDMA, DM Act 2005). With labelled diagrams, tables and PYQs + full model answers.

UPSC Prelims · Mains GS-I & GS-III Seasons · Koppen ~44 min read Droughts · Floods Very High Weight

1.The Four Seasons — Overview
2.Winter (Cold Weather) Season
3.Hot Weather / Pre-Monsoon & Local Storms
4.SW Monsoon & Retreating Seasons
5.Koppen Climatic Classification
6.Stamp & Trewartha Classifications
7.Droughts — Types & Prone Areas
8.Floods — Causes & Types
9.Cross-border & Disaster Management
10.Significance & GS Synthesis
11.Current Affairs Link
12.Prelims PYQs
13.Mains PYQs + Model Answers
★15-Minute Revision Box

Conceptual Clarity — Why this Chapter Matters

Seasons, local storms and the Koppen map are steady Prelims fodder; droughts & floods are heavy GS-III (disaster management). Sort your prep three ways:

Definitional / static: the four seasons & their winds; local storms (loo, kalbaisakhi/nor'westers, mango showers, blossom showers, mahawat/western disturbances); Koppen letter codes (Amw, As, Aw, BWhw, BShw, Cwg, Dfc, E).
Statement-elimination: mango showers (Kerala/Karnataka pre-monsoon), kalbaisakhi (Bengal/Assam), loo (NW plains); DPAP vs DDP; drought types (meteorological, hydrological, agricultural); NDMA & the DM Act 2005.
Applied / synthesis (Mains GS-I & GS-III): why India faces drought & flood together, urban-flood governance, cross-border flood cooperation, and drought-proofing. Needs concept + example + judgement.

Territorial note: western disturbances bring winter rain/snow to the whole northern belt including Jammu & Kashmir and Ladakh, which are Indian sovereign territory; the LoC and LAC are not settled international borders.

1. The Four Seasons — Overview

The IMD recognises four seasons in India, set by the advance and retreat of the monsoon.

Fig 11.1 — India's four seasons and their signature weather: winter (western disturbances), hot pre-monsoon (loo & local storms), SW monsoon (the rains), and retreating/NE monsoon (Tamil Nadu rain & cyclones).

Season	Months	Character
Cold weather (winter)	Dec–Feb	Cool, dry; western disturbances in NW
Hot weather (pre-monsoon)	Mar–May	Hot, dry; loo & local storms
SW monsoon (rainy)	Jun–Sep	Main rains; onset, advance, breaks
Retreating monsoon (autumn)	Oct–Nov	Withdrawal; NE monsoon on SE coast; cyclones

Prelims lock: four IMD seasons — winter (Dec–Feb), hot pre-monsoon (Mar–May), SW monsoon (Jun–Sep), retreating/NE monsoon (Oct–Nov).

2. Winter (Cold Weather) Season

From December to February, the sun is over the southern hemisphere; the north cools sharply while the south stays mild.

Temperature: cold in the north (frost, snow in the hills); mild in the south (moderated by the sea & low latitude).
Winds: dry offshore NE trades; clear skies, low humidity.
Western disturbances: eastward-moving mid-latitude systems from the Mediterranean bring rain/snow to the NW Himalaya & plains — the mahawat rain vital for rabi wheat.
NE monsoon: gives the Tamil Nadu (Coromandel) coast its main rainfall.

Why winter rain matters: the small but well-timed western-disturbance (mahawat) rain is crucial for the standing rabi wheat crop in Punjab, Haryana & western UP — a little rain of great value.

3. Hot Weather / Pre-Monsoon & Local Storms

March–May brings intense heating, low pressure over the north-west, and a family of violent local storms — a favourite exam theme.

Local storm / wind	Region	Note
Loo	NW plains (Punjab to Bihar)	Hot, dry, dusty afternoon wind; heat-stroke risk
Kalbaisakhi / Nor'westers	West Bengal & Assam	Violent evening thunderstorms ("calamity of Baisakh"); some rain & hail
Bardoli Chheerha	Assam	Local name for the nor'wester
Mango showers	Kerala & coastal Karnataka	Pre-monsoon showers that ripen mangoes
Blossom showers	Kerala/Karnataka	Help coffee flowers bloom
Cherry blossom	Karnataka (coffee)	Another pre-monsoon coffee shower

Loo: the searing NW summer wind; prolonged loo causes heat-wave deaths.
Kalbaisakhi: Bengal/Assam evening thunderstorms — destructive but bring welcome pre-monsoon rain (good for jute & tea).
Mango & blossom showers: localised pre-monsoon rains of the south-west that aid mango ripening & coffee flowering.

Prelims lock: loo (NW plains), kalbaisakhi/nor'westers (Bengal–Assam), mango showers & blossom showers (Kerala/Karnataka) — classic local-storm–region matching.

4. SW Monsoon & Retreating Seasons

The rainy and post-rainy seasons complete the annual cycle (covered mechanistically in Topic 10).

SW monsoon (Jun–Sep): onset over Kerala ~1 June; two branches; breaks; the country's main rains (~80% of annual total).
Retreating monsoon (Oct–Nov): withdrawal from NW; clear skies & high humidity give sultry "October heat"; NE monsoon rains Tamil Nadu; peak Bay-of-Bengal cyclone season.

Prelims lock: the retreating-monsoon season (Oct–Nov) brings "October heat," the NE-monsoon rains to Tamil Nadu, and the peak of east-coast tropical cyclones.

5. Koppen Climatic Classification

Koppen's scheme (based on temperature, rainfall & vegetation) is the most used classification for India. Codes combine a main letter (A/B/C/D/E) with rainfall/temperature sub-letters.

Koppen type	Climate	Where in India
Amw	Tropical monsoon (short dry)	West coast (Malabar/Konkan), parts of NE
As	Tropical, dry summer	Coromandel (Tamil Nadu) coast
Aw	Tropical savanna (dry winter)	Most of the peninsula
BShw	Semi-arid steppe (hot)	NW India, rain-shadow of Ghats
BWhw	Hot desert	Thar (western Rajasthan)
Cwg	Humid subtropical (dry winter)	Ganga plains, NE, sub-Himalaya
Dfc	Cold humid (short summer)	Arunachal / higher NE
E	Polar / tundra (high mountain)	Himalaya (high altitude)

Reading the code: A = tropical, B = dry, C = warm-temperate, D = cold, E = polar; 'w' = dry winter, 's' = dry summer, 'm' = monsoon, 'g' = Ganga type (hottest month before the rains), 'h' = hot.

Prelims lock: Thar = BWhw (hot desert); most peninsula = Aw (savanna); Ganga plains = Cwg; Coromandel = As; west coast/NE = Amw; high Himalaya = E.

6. Stamp & Trewartha Classifications

Besides Koppen, Indian climatologists use other schemes.

L. D. Stamp: divided India by the 18°C January isotherm into Temperate/Continental (north) and Tropical (south) India, then into rainfall-based regions.
Trewartha: a modification of Koppen, simplifying the boundaries.
Thornthwaite: based on precipitation-effectiveness & evapotranspiration (moisture index).

Concept: classifications differ in their criteria (temperature, rainfall, vegetation, water balance) but agree broadly — a wet coastal/NE fringe, a savanna peninsula, an arid NW, and a cold Himalayan belt.

7. Droughts — Types & Prone Areas

A drought is a prolonged shortfall of water relative to normal, driven by monsoon failure. India's droughts have several types & a well-mapped prone zone.

Type	Meaning
Meteorological	Rainfall well below normal (deficit ≥25–50%)
Hydrological	Depleted rivers, reservoirs & groundwater
Agricultural	Soil-moisture shortfall harming crops
Socio-economic / ecological	Water shortage hits livelihoods & ecosystems

Drought-prone areas: the arid/semi-arid rain-shadow belt — western Rajasthan, interior Deccan (Marathwada, Rayalaseema), parts of Gujarat, Karnataka, Telangana & MP.
Causes: monsoon failure (El Nino), high variability, over-extraction, deforestation, cropping mismatch.
Programmes: Drought Prone Areas Programme (DPAP) & Desert Development Programme (DDP) — watershed-based drought-proofing (now under integrated watershed schemes).

Prelims lock: drought types — meteorological / hydrological / agricultural / socio-economic; DPAP (drought-prone) & DDP (desert) are the classic drought-proofing programmes; western Rajasthan & interior Deccan are most prone.

8. Floods — Causes & Types

Floods — excess water submerging land — are India's most frequent disaster, the flip side of the same monsoon that brings drought.

Flood type	Where / how
River (riverine) floods	Ganga–Brahmaputra plains, Kosi — silt, low gradient, embankment failure
Flash floods	Hills & cloudbursts (Uttarakhand, Himachal) — sudden, violent
Urban floods	Mumbai, Chennai, Bengaluru — poor drainage, encroached wetlands, concretisation
Coastal floods	Cyclone storm-surge on the east coast & deltas
GLOF	Glacial-lake outburst in the Himalaya (Sikkim/Teesta)

Most flood-prone: the Ganga–Brahmaputra–Barak plains (Assam, Bihar, UP, WB) — heavy rain + silt + low gradient.
Urban floods: a growing hazard from unplanned growth, lost wetlands & choked storm drains.
Causes: intense monsoon bursts, siltation, deforestation, encroachment of floodplains & drainage, dam mismanagement.

Drought & flood together: India regularly suffers drought and flood in the same year — a symptom of a variable, poorly-stored monsoon and degraded catchments. Floodplain zoning & catchment restoration matter more than embankments alone. check for latest update or data

9. Cross-border & Disaster Management

Many Indian floods originate upstream in Nepal, Bhutan or China, and all sit within a national disaster-management framework.

Cross-border floods: the Kosi, Gandak, Ghaghara (Nepal) & Brahmaputra (China) rise abroad — needing data-sharing, joint reservoirs & flood-forecasting cooperation.
DM Act 2005: created the NDMA (National Disaster Management Authority, PM-chaired), SDMAs, and the NDRF.
Institutions: CWC (flood forecasting), IMD (warnings), INCOIS (storm-surge/tsunami), NDMA guidelines on floods, droughts & urban flooding.
Sendai Framework: India follows the global Sendai Framework for Disaster Risk Reduction (prevention & resilience over relief).

Prelims lock: the DM Act 2005 set up the NDMA (chaired by the PM) & NDRF; CWC does flood forecasting; INCOIS handles storm-surge/tsunami; India follows the Sendai Framework.

10. Significance & GS Synthesis

Seasons set India's agricultural calendar; droughts and floods test its resilience — both flow from the same variable monsoon.

Agricultural: seasons & local storms time the kharif & rabi crops; western disturbances save the wheat.
Hazard: drought (rain-shadow west) & flood (Ganga–Brahmaputra plains) coexist — needing storage, watershed & floodplain management.
Governance: disaster management has shifted from relief to preparedness & risk reduction (NDMA, Sendai).
Climate change: more erratic rain intensifies both droughts & floods — a defining GS-III challenge.

GS synthesis: drought and flood are two faces of one variable monsoon over degraded catchments. The single logic: store & spread the monsoon, restore catchments & floodplains, and shift from relief to risk reduction.

11. Current Affairs & Contemporary Relevance (2024–2026)

Seasons-and-hazards stay "current" through heat-waves, monsoon extremes, urban floods, GLOFs and disaster-management reforms — verify the latest status. check for latest update or data

11.1 Heat-waves & drought

Heat-waves & deficit monsoons: intensifying pre-monsoon heat-waves (loo) and El Nino-year drought stress keep drought-proofing topical. check for latest update or data

11.2 Floods & cloudbursts

Urban floods & GLOFs: recurring Mumbai/Chennai/Bengaluru urban floods, Himalayan cloudbursts and the Sikkim/Teesta GLOF (2023) underline flood-risk governance. check for latest update or data

11.3 Disaster-management reform

NDMA & Sendai: updated NDMA guidelines, DM Act amendments and Sendai-aligned risk-reduction push a shift from relief to preparedness. check for latest update or data

11.4 Why it matters

Development	Why it matters for UPSC
Heat-waves	Public health & disaster mgmt (GS-III).
Urban floods	Urban governance & planning (GS-I/III).
Cross-border floods	Regional cooperation (GS-II).
NDMA reforms	Disaster governance (GS-III).

Recurring exam hooks:

Local storms & seasons · Koppen types (evergreen Prelims).
Drought types & DPAP/DDP · NDMA/DM Act (favourite factual sets).
Urban floods · drought-flood paradox · disaster risk reduction (evergreen Mains GS-III).

12. Prelims PYQs (exam-style, high-frequency themes)

Objective questions anchored to genuinely tested UPSC themes on India's seasons, climatic divisions, droughts and floods. Each carries a worked rationale.

UPSC Prelims — exam-style

Q: "Mango showers" are pre-monsoon showers most associated with:

(a) West Bengal & Assam
(b) Kerala & coastal Karnataka
(c) Punjab & Haryana
(d) Tamil Nadu

Answer: (b) Mango showers are pre-monsoon showers over Kerala & coastal Karnataka that ripen mangoes; blossom showers help coffee flower there. Kalbaisakhi = Bengal/Assam.

UPSC Prelims — exam-style

Q: The violent pre-monsoon evening thunderstorms of West Bengal and Assam are called:

(a) Loo
(b) Kalbaisakhi / Nor'westers
(c) Mango showers
(d) Mahawat

Answer: (b) Kalbaisakhi ("calamity of Baisakh") / nor'westers are violent Bengal–Assam pre-monsoon thunderstorms; they help jute & tea. Loo = hot NW wind; mahawat = winter rain.

UPSC Prelims — exam-style

Q: In the Koppen classification, the Thar Desert of western Rajasthan is classified as:

(a) Aw
(b) Cwg
(c) BWhw
(d) Amw

Answer: (c) BWhw = hot desert (Thar). Aw = peninsular savanna; Cwg = Ganga plains; Amw = west coast/NE monsoon type.

UPSC Prelims — exam-style

Q: The winter rain in north-west India, valuable for the rabi wheat crop, is brought by:

(a) Western disturbances
(b) The south-west monsoon
(c) The north-east monsoon
(d) The loo

Answer: (a) Western disturbances (Mediterranean-origin systems on the westerly jet) bring the mahawat winter rain/snow vital for rabi wheat.

UPSC Prelims — exam-style

Q: Consider the following types of drought:

1. Meteorological 2. Hydrological 3. Agricultural

Which of these are recognised categories?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1, 2 and 3
(d) 1 and 3 only

Answer: (c) All three — meteorological (rain deficit), hydrological (depleted water bodies) and agricultural (soil-moisture stress); a fourth is socio-economic/ecological drought.

UPSC Prelims — exam-style

Q: The National Disaster Management Authority (NDMA) was constituted under the:

(a) Environment Protection Act 1986
(b) Disaster Management Act 2005
(c) National Green Tribunal Act 2010
(d) Water Act 1974

Answer: (b) The Disaster Management Act 2005 created the NDMA (chaired by the PM), SDMAs and the NDRF.

UPSC Prelims — exam-style

Q: The "loo" is best described as a:

(a) Hot, dry, dusty afternoon wind of the north-west plains in summer
(b) Cold winter wind from Central Asia
(c) Pre-monsoon shower of the south
(d) Sea breeze of the west coast

Answer: (a) The loo is a hot, dry, dusty summer afternoon wind of the NW plains (Punjab to Bihar); prolonged exposure causes heat-stroke.

UPSC Prelims — exam-style

Q: The most flood-prone region of India is the:

(a) Ganga–Brahmaputra plains
(b) Thar Desert
(c) Deccan Plateau interior
(d) Western Ghats crest

Answer: (a) The Ganga–Brahmaputra–Barak plains (Assam, Bihar, UP, WB) are the most flood-prone — heavy rain, high silt, low gradient and the Kosi's shifting course.

Prelims — anticipated themes

Likely: four seasons · local storms (loo/kalbaisakhi/mango-blossom showers) · western disturbances/mahawat · Koppen types (BWhw/Aw/Cwg/Amw/As) · drought types & DPAP/DDP · flood types & prone areas · NDMA/DM Act 2005 · Sendai Framework. check for latest update or data

13. Mains PYQs + Model Answers

Genuine UPSC GS-I/GS-III themes on India's seasons, droughts and floods. Each carries a full answer skeleton — Introduction → body → Conclusion.

UPSC Mains GS-III — style 15 marks · 250 words

Q: India faces droughts and floods simultaneously. Analyse the causes and suggest an integrated management strategy.

Model Answer

Introduction: India regularly suffers drought in the rain-shadow west and flood in the Ganga–Brahmaputra plains in the same year — a paradox of one variable monsoon.
Drought causes: monsoon failure (El Nino), high variability, over-extraction, deforestation, cropping mismatch in dry zones.
Flood causes: intense bursts, siltation, low gradient, floodplain & wetland encroachment, poor drainage (urban floods).
Integrated strategy: store & recharge monsoon water, watershed development, floodplain zoning, catchment restoration, crop diversification, forecasting & NDMA-led preparedness.
Conclusion: managing the same water across space and time — storing surplus, spreading it to deficits — is the integrated answer.

UPSC Mains GS-I — style 15 marks · 250 words

Q: Describe the characteristics of India's seasons and the local storms associated with the pre-monsoon period.

Model Answer

Introduction: India's four seasons are defined by the monsoon's advance and retreat, each with distinct weather.
Seasons: cold winter (western disturbances, NE monsoon), hot pre-monsoon (loo, local storms), SW monsoon (main rains), retreating monsoon (October heat, cyclones).
Pre-monsoon storms: loo (NW plains), kalbaisakhi/nor'westers (Bengal–Assam), mango & blossom showers (Kerala/Karnataka).
Utility: these storms aid tea, jute, mango & coffee even as the loo causes heat-waves.
Conclusion: India's seasonal rhythm and its local storms together shape agriculture and daily life.

UPSC Mains GS-III — style 15 marks · 250 words

Q: Urban flooding has become a recurring disaster in Indian cities. Examine its causes and remedies.

Model Answer

Introduction: Mumbai, Chennai and Bengaluru now flood almost yearly — a man-made urban disaster.
Causes: unplanned growth, encroached lakes/wetlands, concretisation reducing infiltration, choked & undersized storm drains, extreme rain bursts.
Impacts: loss of life, economic disruption, disease, and damage to infrastructure.
Remedies: protect wetlands, sponge-city permeable design, desilting & expanding drains, early-warning, floodplain zoning, NDMA urban-flood guidelines.
Conclusion: urban flooding needs planning & ecological restoration, not just bigger drains.

UPSC Mains GS-III — style 15 marks · 250 words

Q: Discuss India's disaster-management framework and its shift from relief to risk reduction.

Model Answer

Introduction: the DM Act 2005 reoriented India from reactive relief toward proactive disaster-risk reduction.
Framework: NDMA (PM-chaired), SDMAs, DDMAs, NDRF; CWC, IMD, INCOIS for forecasting/warnings; national & hazard-specific guidelines.
Shift: emphasis on prevention, mitigation, preparedness & resilience aligned with the Sendai Framework.
Challenges: capacity gaps, coordination, funding, and integrating climate-risk into planning.
Conclusion: resilience-building and early warning, not relief alone, define modern disaster governance.

UPSC Mains GS-I — style 10 marks · 150 words

Q: On what basis did Koppen classify India's climate? Give major types with examples.

Model Answer

Introduction: Koppen classified climate using temperature, rainfall and natural vegetation, with letter codes.
Major Indian types: Aw (peninsular savanna), Amw (west coast/NE monsoon), As (Coromandel), BShw/BWhw (semi-arid/desert NW), Cwg (Ganga plains), E (high Himalaya).
Reading codes: main letter (A/B/C/D/E) + sub-letters for rainfall/temperature season (w = dry winter, s = dry summer, g = Ganga type).
Conclusion: Koppen captures India's wet fringe, savanna core, arid NW and cold Himalaya in a compact scheme.

Mains — anticipated themes

Likely: drought-flood paradox & integrated management · seasons & local storms · urban flooding · disaster framework & Sendai · Koppen classification · cross-border floods. check for latest update or data

15-Minute Revision Box

Must-Remember Facts — Seasons, Climatic Divisions, Droughts & Floods

Four seasons:

Winter (Dec–Feb): W. disturbances, mahawat, NE monsoon
Hot pre-monsoon (Mar–May): loo, local storms
SW monsoon (Jun–Sep); Retreating (Oct–Nov)

Local storms:

Loo — NW plains (hot dry)
Kalbaisakhi/nor'westers — Bengal–Assam
Mango & blossom showers — Kerala/Karnataka
Western disturbances/mahawat — NW winter

Koppen types:

BWhw = Thar desert; Aw = peninsula savanna
Cwg = Ganga plains; As = Coromandel
Amw = W coast/NE; E = high Himalaya

Droughts:

Types: meteorological / hydrological / agricultural / socio-economic
Prone: W Rajasthan, interior Deccan (Marathwada, Rayalaseema)
DPAP (drought-prone) + DDP (desert) programmes

Floods:

Most-prone: Ganga–Brahmaputra plains (Assam, Bihar)
Types: river, flash, urban, coastal, GLOF
Urban: Mumbai/Chennai/Bengaluru (drainage, wetlands)

Disaster framework:

DM Act 2005 → NDMA (PM), SDMA, NDRF
CWC (floods), IMD (warnings), INCOIS (surge)
Sendai Framework (risk reduction)

Highest-frequency themes: local storms · Koppen types · drought types & DPAP/DDP · flood types & prone areas · NDMA/DM Act. One logic: drought & flood are two faces of one variable monsoon over degraded catchments — store, spread, restore, and reduce risk.

Storm	Region
Loo	NW plains
Kalbaisakhi	Bengal–Assam
Mango showers	Kerala/Karnataka
Mahawat	NW winter

Topic 11: Seasons, Climatic Divisions, Droughts & Floods

On this page

Conceptual Clarity — Why this Chapter Matters

1. The Four Seasons — Overview

2. Winter (Cold Weather) Season

3. Hot Weather / Pre-Monsoon & Local Storms

4. SW Monsoon & Retreating Seasons

5. Koppen Climatic Classification

6. Stamp & Trewartha Classifications

7. Droughts — Types & Prone Areas

8. Floods — Causes & Types

9. Cross-border & Disaster Management

10. Significance & GS Synthesis

11. Current Affairs & Contemporary Relevance (2024–2026)

11.1 Heat-waves & drought

11.2 Floods & cloudbursts

11.3 Disaster-management reform

11.4 Why it matters

12. Prelims PYQs (exam-style, high-frequency themes)

13. Mains PYQs + Model Answers

Model Answer

Model Answer

Model Answer

Model Answer

Model Answer

15-Minute Revision Box

Must-Remember Facts — Seasons, Climatic Divisions, Droughts & Floods