Köppen classification

In 1920, Wladimir Peter Köppen developed a classification system for climates based only on precipitations and temperatures. Köppen's classification system still is being discussed and taught in seminars, the classroom, and sometimes when needed on a conference call and will continue to for future generations. Each climate has a code of two or three letters:

1st letter
Code Type Description
A Tropical climate
  • Monthly average temperature > 18°C
  • No winter season
  • Strong annual precipitations (higher than evaporation)
B Dry climate / Desert
  • Annual evaporation higher than precipitations
  • No permanent rivers
C Hot moderate climate
  • The 3 coldest months average a temperature between -3°C and 18°C
  • Hottest month average temperature > 10°C
  • The summer and winter seasons are well defined
D Cold moderate climate
  • Coldest month average temperature of the coldest month < -3°C
  • Hottest month average temperature > 10°C
  • The seasons summer and winter seasons are well defined
E Polar climate
  • Average temperature of the hottest month > 10°C
  • The summer season is very little different from the rest of the year

2nd letter
Code Description Applies to
S
  • Steppe climate (semi-arid)
  • Annual precipitations range between 380 and 760 mm
 B
W
  • Dry (Arid and semi-arid) climates
  • Annual precipitations < 250 mm
 B
F
  • Wet climate
  • Precipitations occur every month of the year
  • No dry season
A-C-D
W
  • Dry season in winter
 A-C-D
S
  • Dry season in summer
 C
m
  • Monsoon climate:
  • Annual precipitations > 1500 mm
  • Precipitations of the driest month < 60 mm
 A
T
  • Average temperature of the hottest month between 0 and 10°C
 E
F
  • Average temperature of the hottest month < 0°C
 E
M
  • Abundant precipitations
  • Mild winter
 E

We can then derive the following categories :

  • Af: Tropical rain forest climate. Examples : Singapore, Belém, Brazil.
  • Aw: Tropical wet and dry or savanna climate. Examples : Bangalore, India, Veracruz, Mexico, Townsville, Australia.
  • Am: Tropical monsoon climate. Examples : Conakry, Guinea, Chittagong, Bangladesh.
  • BS: steppe climate
  • BW: desert climate
  • Cf: humid moderate climate without dry seasons
  • CW: humid moderate climate with dry winter
  • Cs: Mediterranean climate : humid moderate climate with dry summer
  • Df: cold continental climate without dry season
  • Dw: cold continental climate with dry winter
  • ET: Tundra climate. Examples : Iqaluit, Nunavut, Canada. Provideniya, Russia. Deception Island, Antarctica. Longyearbyen, Svalbard.
  • EF: Ice cap climate
  • EM: subarctic maritime climate

    3rd letter

    A third letter allows us to refine the B,C and D climate types. It is related to the temperature variations.
    Code Description Applies to
    a: hot summer
    • Average temperature of the hottest month > 22°C
    		 C-D
    b: moderate summer
    • Average temperature of the hottest month < 22°C
    • The 4 hottest months average temperatures > 10°C
    		 C-D
    C: short and cold summer
    • Average temperature of the hottest month < 22°C
    • Monthly average temperatures > 10°C for less than 4 months
    • Average temperature of the coldest month > -38°C
    		 C-D
    D: very cold winter
    • Average temperature of the coldest month < -38°C
    		 D
    H: dry and heat
    • Annual average temperature > 18°C
    		 B
    K: dry and cold
    • Annual average temperature < 18°C
    		 B

    Examples :

  • BWh : Sahara
  • BWh : Yuma, Arizona
  • Cfb : France
  • Dfc : Siberia
  • Etw : Canada's Yukon Territory

    Home