CDS Geography · Climatology, Atmosphere and Weather
Climate Types and Koppen's Scheme
How Koppen's capital and small letters name a climate, which Koppen types cover which parts of India, and how to recognise the world's climate types from their features.
Why this matters
Eleven CDS questions from 2018 to 2025: 8 MODERATE, 3 HARD. Five turn on Koppen's letters or names. Two 2025 items describe a climate in three statements, in NCERT's own words, and ask you to name it.
Concept 1 of 3: Koppen's letters
Koppen sorted the world's climates by temperature and rain, the two things that decide what plants can grow. A capital letter gives the main group. A second letter gives the dry season (or, for dry climates, how dry). A third letter adds detail about heat or cold. Read the code one letter at a time.
Definition
Capital letters, the main groups (NCERT Class 11):
- A Tropical: coldest month 18 °C or warmer.
- B Dry: evaporation is more than precipitation. BW = desert (arid); BS = steppe (semi-arid).
- C Warm temperate (mid-latitude, also called mesothermal): coldest month between minus 3 °C and 18 °C.
- D Cold snow forest: coldest month minus 3 °C or colder.
- E Cold (polar): every month below 10 °C. ET = tundra; EF = ice cap, no month above 0 °C (interior Greenland and Antarctica).
- H Highland: cold because of height.
Small letters:
- f no dry season; m monsoon, a short dry season; w winter dry season; s summer dry season.
- In B climates, h = hot (subtropical) and k = cold (mid-latitude).
| Code | Name | Main feature |
|---|---|---|
| Af | Tropical wet | No dry season |
| Am | Tropical monsoon | Short dry season |
| Aw | Tropical wet and dry (savanna) | Winter dry seasonQ CDS 2020 (II): Aw is the tropical savannah climate, not Am, Cwg or Dfc. |
| BSh | Subtropical steppe | Low-latitude semi-arid |
| BWh | Subtropical desert | Low-latitude arid |
| BSk | Mid-latitude steppe | Mid-latitude semi-aridQ CDS 2025 (II): three of four pairs from this table were right; marine west coast was wrongly given a severely cold summer. |
| BWk | Mid-latitude desert | Mid-latitude arid |
| Cfa | Humid subtropical | No dry season, warm summer |
| Cs | Mediterranean | Dry, hot summer |
| Cfb | Marine west coast | No dry season, warm and cool summer |
| Df | Humid continental | No dry season, severe winter |
| Dw | Subarctic (cold climate with dry winters) | Winter dry and very severe |
| ET | Tundra | No true summer |
| EF | Ice cap | Perennial ice, no month above 0 °C |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2024 · CDS (I) 2024 — General Knowledge · Q86Moderate
Example 1 · Climatology, Atmosphere and Weather · Climate Types
What does BW stand for as per the Koeppen climate classification?
W is desert, S is steppe
Inside the dry group B, capital W means desert (arid) and capital S means steppe (semi-arid). Do not mix them with the small w (winter dry season) and s (summer dry season).
Marine west coast summers are mild
Cfb, the marine west coast type, has no dry season and mild (warm and cool) summers. A 'severely cold summer' describes no Koppen C type.
Concept 2 of 3: Koppen types in India
India spans hot deserts, wet coasts, the Ganga plain and the Himalaya, so it holds many Koppen types. The south, close to the sea and the equator, stays warm and even all year. The interior north swings between very hot and quite cold.
Definition
NCERT Class 11 (India: Physical Environment) map of Koppen types:
- Amw: the west coast south of Goa (monsoon with a short dry season).
- As: the Coromandel coast of Tamil Nadu (dry in summer, rain in winter).
- Aw: most of the peninsular plateaus south of the Tropic of Cancer (tropical savanna).
- BShw: north-western Gujarat, parts of western Rajasthan and Punjab (semi-arid steppe).
- BWhw: extreme western Rajasthan (hot desert).
- Cwg: the Ganga plain, eastern Rajasthan, northern Madhya Pradesh, most of the north-east.
- Dfc: Arunachal Pradesh. E (polar type): Jammu and Kashmir, Himachal Pradesh and Uttarakhand.
Sea versus interior:
- South India, near the sea on three sides and near the equator, has a small daily and yearly range of temperature and high temperatures all year: no extremes.
- The interior north has a continental climate: a large range between summer and winter.
| Koppen type | Region of India |
|---|---|
| Amw | West coast south of Goa |
| As | Coromandel coast of Tamil Nadu |
| Aw | Most of the peninsular plateaus |
| BShw | North-western Gujarat, parts of western Rajasthan and Punjab |
| BWhw | Extreme western Rajasthan |
| Cwg | Ganga plain, eastern Rajasthan, northern Madhya Pradesh, most of the north-east |
| Dfc | Arunachal Pradesh |
| E | Jammu and Kashmir, Himachal Pradesh, Uttarakhand |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2022 · CDS (I) 2022 — General Knowledge · Q32Hard
Example 2 · Climatology, Atmosphere and Weather · Climate Types
Which one of the following climatic types (Köppen's Scheme) is best suited to describe the climate of the western fringe of Rajasthan ?
South India is not extreme
Near the sea and the equator, South India has small daily and annual ranges and stays hot all year. 'Extreme climatic conditions' is the false statement about it.
BWhw is only the far west
The hot desert type BWhw covers only extreme western Rajasthan. The rest of the dry north-west (north-western Gujarat, parts of Rajasthan and Punjab) is the semi-arid BShw.
Concept 3 of 3: World climate types from their features
Many CDS items describe a climate in three statements and ask for its name. Each type has one tell-tale feature: the Mediterranean has its dry summer, the savanna its long dry season, the tundra its tiny summer, the Siberian type its winter high pressure.
Definition
The types CDS has described (NCERT Class 11):
- Tropical wet and dry (Aw, savanna, 'Sudan type'): hot all year; rain is variable, with a short wet season and a longer dry season. Found north and south of the Amazon forest (Brazil, Bolivia, Paraguay) and in Sudan and south of Central Africa.
- Mediterranean (Cs): dry, hot summer and mild, rainy winter; on the west sides of continents between about 30° and 40°.
- Cold climate with dry winters (Dw): mainly north-east Asia. Strong winter anticyclones that weaken in summer cause a monsoon-like reversal of wind; precipitation is low, about 12 to 15 cm; summers get cooler polewards.
- Tundra (ET): no true summer and a very short warm growing season, so few species live there: mosses, lichens, small shrubs.
| Climate | Tell-tale feature | Where |
|---|---|---|
| Tropical wet and dry (savanna) | Short wet season, long dry season | Sudan; Paraguay, Bolivia, Brazil |
| Mediterranean | Dry summer, rainy winter | West sides of continents, 30° to 40°Q CDS 2019 (II): the most noticeable feature is the dry summer, not a dry winter. |
| Cold climate with dry winters | Winter anticyclone, monsoon-like wind reversal, 12 to 15 cm a year | North-east AsiaQ CDS 2025 (II): named from three statements, ahead of tundra and steppe. |
| Tundra | Very short warm season, few species | Arctic fringes of North America and EurasiaQ CDS 2018 (I): low biodiversity, and the short warm season is the reason. |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2025 · CDS (I) 2025 — General Knowledge · Q6Moderate
Example 3 · Climatology, Atmosphere and Weather · Climate Types
Identify the type of climate on the basis of the following characteristics relating to it :
I. Temperature is high throughout the year.
II. Rainfall is variable with a short wet season and a longer dry season.
III. Climate of Sudan and Paraguay is an example of this climate type.
Select the answer using the code given below :
The Mediterranean is dry in summer
Most climates get their rain in summer. The Mediterranean is the exception: its summer is dry and its winter is wet. An option saying 'dry winter' is wrong.
Monsoon-like winds outside the tropics
A monsoon-like reversal of winds caused by winter anticyclones points to the cold climate with dry winters of north-east Asia, not to the tropical monsoon.
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (3)
Koppen's letters14 rows
| Code | Name | Main feature |
|---|---|---|
| Af | Tropical wet | No dry season |
| Am | Tropical monsoon | Short dry season |
| Aw | Tropical wet and dry (savanna) | Winter dry seasonQ CDS 2020 (II): Aw is the tropical savannah climate, not Am, Cwg or Dfc. |
| BSh | Subtropical steppe | Low-latitude semi-arid |
| BWh | Subtropical desert | Low-latitude arid |
| BSk | Mid-latitude steppe | Mid-latitude semi-aridQ CDS 2025 (II): three of four pairs from this table were right; marine west coast was wrongly given a severely cold summer. |
| BWk | Mid-latitude desert | Mid-latitude arid |
| Cfa | Humid subtropical | No dry season, warm summer |
| Cs | Mediterranean | Dry, hot summer |
| Cfb | Marine west coast | No dry season, warm and cool summer |
| Df | Humid continental | No dry season, severe winter |
| Dw | Subarctic (cold climate with dry winters) | Winter dry and very severe |
| ET | Tundra | No true summer |
| EF | Ice cap | Perennial ice, no month above 0 °C |
Koppen types in India8 rows
| Koppen type | Region of India |
|---|---|
| Amw | West coast south of Goa |
| As | Coromandel coast of Tamil Nadu |
| Aw | Most of the peninsular plateaus |
| BShw | North-western Gujarat, parts of western Rajasthan and Punjab |
| BWhw | Extreme western Rajasthan |
| Cwg | Ganga plain, eastern Rajasthan, northern Madhya Pradesh, most of the north-east |
| Dfc | Arunachal Pradesh |
| E | Jammu and Kashmir, Himachal Pradesh, Uttarakhand |
World climate types from their features4 rows
| Climate | Tell-tale feature | Where |
|---|---|---|
| Tropical wet and dry (savanna) | Short wet season, long dry season | Sudan; Paraguay, Bolivia, Brazil |
| Mediterranean | Dry summer, rainy winter | West sides of continents, 30° to 40°Q CDS 2019 (II): the most noticeable feature is the dry summer, not a dry winter. |
| Cold climate with dry winters | Winter anticyclone, monsoon-like wind reversal, 12 to 15 cm a year | North-east AsiaQ CDS 2025 (II): named from three statements, ahead of tundra and steppe. |
| Tundra | Very short warm season, few species | Arctic fringes of North America and EurasiaQ CDS 2018 (I): low biodiversity, and the short warm season is the reason. |
Watch out for (6)
- W is desert, S is steppe→ Koppen's letters
- Marine west coast summers are mild→ Koppen's letters
- South India is not extreme→ Koppen types in India
- BWhw is only the far west→ Koppen types in India
- The Mediterranean is dry in summer→ World climate types from their features
- Monsoon-like winds outside the tropics→ World climate types from their features
Test yourself on Climatology, Atmosphere and Weather
15 past CDS questions from this chapter, timed at 15 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.