The vast latitudinal extent, diverse physiography, and seasonal monsoon reversals of the Indian subcontinent create a complex matrix of macro and microclimates. To systematically analyze these variations for geographic and demographic planning, several climatologists have delineated India into distinct climatic zones. The most widely accepted frameworks in contemporary geography are those developed by Wladimir Köppen, Glenn Thomas Trewartha, and Stamp & Kendrew.
Köppen’s Climatic Classification of India
Wladimir Köppen’s empirical system classifies climate based on the relationship between precipitation, temperature, and vegetation distribution. It utilizes specific uppercase and lowercase alphabetical codes to represent critical threshold limits of temperature and rainfall seasonality.
Nomenclature of Köppen’s Alphabetical Codes
- A (Tropical Rainy Climate): Average temperature of the coldest month is 18°C or higher.
- B (Dry Climate): Potential evaporation exceeds annual precipitation.
- C (Warm Temperate/Mesothermal): Average temperature of the coldest month is between -3°C and 18°C.
- D (Cold Snow Forest/Microthermal): Average temperature of the coldest month is below -3°C, and the warmest month is above 10°C.
- E (Polar Climate): Average temperature of the warmest month is below 10°C.
- w (Dry Winter): Rainfall occurs predominantly during the high-sun summer season.
- s (Dry Summer): Rainfall occurs predominantly during the low-sun winter season.
- m (Monsoon Climate): Short dry season with heavy annual rainfall.
- h (Hot Arid): Average annual temperature is above 18°C.
- g (Ganga Type): Warmest month occurs before the summer solstice and the onset of monsoonal rains.
Systematic Grid of Köppen’s Climatic Zones in India
| Climatic Code | Type of Climate | Core Geographic Regions | Principal Meteorological Metrics | Associated Vegetation Type |
| Amw | Tropical Monsoon (Short Dry Season) | Western Coastal Plains, Malabar Coast, Konkan, Tripura, South Assam, Andaman & Nicobar | Annual rainfall >250 cm; winter dry season is brief but intense. | Tropical Evergreen and Semi-Evergreen Forests |
| Aw | Tropical Savanna | Most of Peninsular India, southern Madhya Pradesh, interior Maharashtra, Odisha, Jharkhand | Distinct dry winter season; average annual rainfall varies between 75 cm and 150 cm. | Tropical Deciduous (Monsoon) Forests and Savanna Grasslands |
| As | Tropical Moist (Dry Summer) | Coromandel Coast of Tamil Nadu, adjoining coastal Andhra Pradesh | Summer is dry; receives bulk of precipitation from the Northeast Monsoon (Oct–Dec). | Tropical Dry Evergreen and Thorn Forests |
| Bshw | Semi-Arid Steppe (Hot) | Rain-shadow zone of Western Ghats (Marathwada, Rayalaseema), parts of Karnataka, Gujarat, SW Haryana | Annual rainfall ranges between 30 cm and 75 cm; high temperature variability. | Tropical Thorn and Scrub Forests |
| Bwhw | Hot Desert | Western Rajasthan (Thar Desert), Kutch region of Gujarat | Annual rainfall <25 cm; high diurnal temperature range; extreme summer heat. | Xerophytic Vegetation, Cacti, and Scrub |
| Cwgw | Humid Subtropical (Ganga Type) | Indo-Gangetic Plains, North Madhya Pradesh, Bihar, Uttar Pradesh, West Bengal, Assam Plains | Dry winters; maximum temperature achieved in May before the summer monsoon. | Tropical Moist Deciduous and Riverine Forests |
| Dfc | Cold Humid Winter (Short Summer) | Arunachal Pradesh, Sikkim, higher reaches of Assam hills | Short, cool summers; winters are cold and humid; significant winter snowfall. | Sub-Alpine and Coniferous (Boreal) Forests |
| ET | Tundra Climate | Higher altitudinal belts of the Great Himalayas, Ladakh, Karakoram Range | Temperature of the warmest month drops below 10°C; severe frost hazards. | Alpine Pastures, Mosses, Lichens, and Meadows |
| E | Polar/Highland Climate | Trans-Himalayan regions, inner valleys of Jammu & Kashmir, Himachal Pradesh, Uttarakhand | Permanent snow fields; glaciers; sub-zero average annual temperatures. | Permafrost zones with virtually no tree cover |
Trewartha’s Climatic Framework of India
Glenn Thomas Trewartha modified Köppen’s empirical system to create a more realistic classification that aligns closely with regional vegetation boundaries and physiographical units.
Major Climatic Divisions under Trewartha
Tropical Rainforest Climate (Ar)
This zone encompasses the Western Coastal Plains, the windward slopes of the Western Ghats, and the lowlands of Assam and Meghalaya. It experiences high temperatures year-round (>22°C even in winter) and lacks a true dry season, with annual rainfall consistently exceeding 250 cm.
Tropical Monsoon Climate (Am)
This zone covers the western parts of Peninsular India, parts of West Bengal, and Orissa. It functions with high baseline temperatures but features a distinct, brief dry period during the winter months, supplemented by heavy summer monsoon deluges.
Tropical Savanna Climate (Aw)
Occupying the majority of interior Peninsular India, excluding the rain-shadow belts. It is characterized by hot summers, mild winters, and a prolonged dry winter season. Rainfall is highly seasonal, occurring almost entirely during the Southwest Monsoon.
Tropical Steppe / Semi-Arid Climate (BS)
This region is split into two primary segments: the narrow, elongated rain-shadow strip running parallel to the east of the Western Ghats, and a broad belt across northwestern India covering parts of Rajasthan, Gujarat, Punjab, and Haryana. Temperatures are high, and rainfall is erratic, ranging between 30 cm and 75 cm.
Subtropical Humid Climate (Caf)
This zone spans the entire northern plains of India, from Punjab through Uttar Pradesh, Bihar, to the Brahmaputra Valley. It features hot, oppressive summers, relatively cold winter months (10°C to 15°C), and receives the bulk of its precipitation from summer monsoonal streams, with light winter additions from Western Disturbances.
Mountain / Highland Climate (H)
Restricted to the Himalayan mountain chain. Temperature is determined entirely by vertical zonation and altitude rather than latitude, changing from subtropical at the foothills to alpine tundra at higher elevations.
Stamp and Kendrew’s Simplistic Classification
L. Dudley Stamp and W.G. Kendrew classified India’s climate based primarily on the 18°C January isotherm (lines of equal temperature), dividing the country into two macro-regions: Tropical India (South of the Tropic of Cancer/Isotherm) and Subtropical India (North of the Isotherm).
The Seven Sub-Climatic Regions of Stamp
1. The Himalayan Region (Alpine)
Characterized by cold winters and cool summers, with heavy winter snowfall and summer rain varying by slope exposure.
2. The Northwest Arid Plain (Thar Desert)
Characterized by extreme continentality, high summer temperatures (>45°C), and an average annual rainfall under 25 cm.
3. The Moderately Arid Region
Encompassing the semi-arid plains of Punjab, Haryana, and eastern Rajasthan, where rainfall ranges from 25 cm to 50 cm.
4. The Humid Sub-Himalayan Belt
Stretching across the foot-hills of the Shivalik and Terai regions, featuring moderate temperatures and high orographic rainfall.
5. The Tropical Plateau (Deccan)
Characterized by moderate temperature baselines throughout the year, with seasonal variations in rainfall driven by rain-shadow dynamics.
6. The Humid Malabar Coast
Characterized by low annual ranges of temperature, high relative humidity, and heavy rainfall exceeding 300 cm.
7. The Sub-Humid Coromandel Coast
Characterized by moderate annual temperatures, with maximum precipitation shifting to the winter months (October–December).
High-Yield Facts and Trivia for UPSC Prelims
The As-Asy Paradox of the Coromandel Coast
The Coromandel Coast is classified as As under Köppen’s framework. This indicates a tropical climate with a dry summer season, making it unique within India. While the rest of the country experiences its wet season from June to September via the Southwest Monsoon, the Coromandel Coast is shielded by the Western Ghats rain-shadow. It receives its primary rainfall from October to December when the Northeast Monsoon absorbs moisture over the Bay of Bengal.
The Adiabatic Boundary of the Bshw Zone
The Bshw (Semi-Arid Steppe) zone of the interior Deccan Plateau is a direct product of adiabatic warming. As the moisture-laden winds of the Arabian Sea Branch cross the crest of the Western Ghats, the air descends the eastern slopes, warms under pressure, and its relative humidity drops. This creates a structural dry zone that receives less than 60 cm of rainfall annually.
The Western Ganes Thermal Inversion Layer
In the Cwgw zone of northern India during winter, a strong temperature inversion layer frequently forms near the surface. Clear skies and calm wind fields allow intense terrestrial radiation to cool the ground layer rapidly, trapping moisture and pollutants. This triggers the formation of dense radiation fog and smog across the plains, severely reducing visibility in December and January.
The Dfc Altitudinal Limit
The Dfc climate (Cold Humid Winter with Short Summer) is restricted to the northeastern Himalayan states, primarily Arunachal Pradesh. It differs from the western Himalayan E (Polar) climate because it receives high rainfall from the Bay of Bengal branch. This creates a dense, humid forest landscape at lower elevations that transitions into alpine vegetation at higher altitudes.
The Shift of the Isothermal Axis
Climate monitoring over recent decades has shown a steady northward shift of the 18°C January isotherm. This shift indicates a gradual contraction of the true Cwgw subtropical zone and a corresponding expansion of tropical Aw characteristics into central India, a trend driven by rising global temperatures.
Last Modified: June 5, 2026