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.
On this page
- 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.
| 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 |
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.
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.
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.
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.
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).
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).
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.
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).
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.
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
11.2 Floods & cloudbursts
11.3 Disaster-management reform
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.
Q: "Mango showers" are pre-monsoon showers most associated with:
Answer: (b) Mango showers are pre-monsoon showers over Kerala & coastal Karnataka that ripen mangoes; blossom showers help coffee flower there. Kalbaisakhi = Bengal/Assam.
Q: The violent pre-monsoon evening thunderstorms of West Bengal and Assam are called:
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.
Q: In the Koppen classification, the Thar Desert of western Rajasthan is classified as:
Answer: (c) BWhw = hot desert (Thar). Aw = peninsular savanna; Cwg = Ganga plains; Amw = west coast/NE monsoon type.
Q: The winter rain in north-west India, valuable for the rabi wheat crop, is brought by:
Answer: (a) Western disturbances (Mediterranean-origin systems on the westerly jet) bring the mahawat winter rain/snow vital for rabi wheat.
Q: Consider the following types of drought:
1. Meteorological 2. Hydrological 3. Agricultural
Which of these are recognised categories?
Answer: (c) All three — meteorological (rain deficit), hydrological (depleted water bodies) and agricultural (soil-moisture stress); a fourth is socio-economic/ecological drought.
Q: The National Disaster Management Authority (NDMA) was constituted under the:
Answer: (b) The Disaster Management Act 2005 created the NDMA (chaired by the PM), SDMAs and the NDRF.
Q: The "loo" is best described as a:
Answer: (a) The loo is a hot, dry, dusty summer afternoon wind of the NW plains (Punjab to Bihar); prolonged exposure causes heat-stroke.
Q: The most flood-prone region of India is the:
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.
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.
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.
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.
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.
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.
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.
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
- Winter (Dec–Feb): W. disturbances, mahawat, NE monsoon
- Hot pre-monsoon (Mar–May): loo, local storms
- SW monsoon (Jun–Sep); Retreating (Oct–Nov)
- Loo — NW plains (hot dry)
- Kalbaisakhi/nor'westers — Bengal–Assam
- Mango & blossom showers — Kerala/Karnataka
- Western disturbances/mahawat — NW winter
- BWhw = Thar desert; Aw = peninsula savanna
- Cwg = Ganga plains; As = Coromandel
- Amw = W coast/NE; E = high Himalaya
- Types: meteorological / hydrological / agricultural / socio-economic
- Prone: W Rajasthan, interior Deccan (Marathwada, Rayalaseema)
- DPAP (drought-prone) + DDP (desert) programmes
- Most-prone: Ganga–Brahmaputra plains (Assam, Bihar)
- Types: river, flash, urban, coastal, GLOF
- Urban: Mumbai/Chennai/Bengaluru (drainage, wetlands)
- DM Act 2005 → NDMA (PM), SDMA, NDRF
- CWC (floods), IMD (warnings), INCOIS (surge)
- Sendai Framework (risk reduction)