Koppen Climate Classification

Developed by Wladimir Köppen, the Koppen climate system is one of the most commonly used classification system for climate.

According to this system, local vegetation is the best way to express climate and for this reason climate zone boundaries have been chosen with vegetation distribution; keeping the average monthly and annual temperatures and precipitation and the seasonality of precipitation in mind.

This system divides the climates into five main groups and other further sub divisions. In this system climate types are represented by a 2 to 4 letter symbol.

Group A: Tropical/ Megathermal Climate

Tropical climates are described as continuous high temperatures throughout the year near sea level and low elevation areas. They are subdivided as follows:

• Tropical rainforest climate, represented as Af, with average rainfall of at least 60mm throughout the year.
• Tropical monsoon climate, represented as Am, which is most common in southern Asia and West Africa, and monsoon winds changing their direction according to the seasons.
• Tropical wet and dry or savanna climate, Aw, with dry season, and the driest month have rainfall less than 60 mm.

This climate is described as rainfall less than the required evapotranspiration limit. Precipitation threshold can be calculated by this method:

Average annual temperature (°C) x 20 + 280

• If the results are 70% or more, there is sun half of the year; from April to September in the Northern Hemisphere and from October to March in the Southern.
• If the annual precipitation is less than half the threshold for Group B, it is classified as desert climate, represented as BW; if it is less than the threshold but more than half the threshold, it is classified as steppe climate, represented as BS. The area does not include in group B climate if the climate is more than the threshold, Added ‘h’ signifies low latitude climate with average annual temperature above 18 °C and ‘k’ middle latitude climate with average annual temperature below 18 °C Examples of such regions are Ellinikon, Athens, Greece, represented as BSh; Yuma, Arizona, United States, represented as BWh; Mexicali, Mexico, represented as BWh; Almería, Spain, represented as BWh; Cobar, New South Wales, Australia, represented as BSh; etc.

Group C climates have an average temperature above 10 °C in hot months and between −3 ° C and -18 °C in coldest month. Here second letter indicates the pattern of rainfall and third the degree of summer heat. ‘w’ indicates dry winters, ‘s’ indicates dry summers and ‘f’ indicates a lot of rainfall precipitation in all seasons.

 ‘A’ indicates warmest month with average temperature rising above 22 °C, ‘b’ indicates warmest month with average temperature below 22 °C, and ‘c’ indicates mean temperatures above 10 °C. Group C climates are subdivided into:

• Dry-summer subtropical or Mediterranean climate, represented as Csa, Csb, usually occurring on the western part of continents between the latitudes of 30° and 45°.
• Humid subtropical climatesare represented as Cfa, Cw, occurring in the interiors of continents, or on their east coasts, in the high latitude of 20 and 30.
• Temperate climate with dry winters, represented as Cwb, is a type of climate common to highlands of Mexico, Peru, Bolivia, Madagascar, Zambia, Zimbabwe, South Africa and even in Argentine province of Cordoba.
• Maritime Subarctic climates are Subpolar Oceanic climates represented as Cfc.

These climates have an average temperature above 10 °C in hot months, and cold months having average temperatures below −3 °C, in the interiors of continents, or on their east coasts, north of 40° North latitude.

The second and third letters are used same as in Group C climates, ‘d’ as third letter indicates three or lesser months with mean temperatures above 10 °C and a coldest month temperature below −38 °C. Group D climates are subdivided into:

• Hot Summer Continental climates, represented as Dfa, Dwa, Dsa,
• Warm Summer Continental or Hemiboreal climates are represented as Dfb, Dwb, Dsb
• Continental Subarctic or Boreal (taiga) climates are represented as Dfc, Dwc, Dsc
• Continental Subarctic climates with extremely severe winters as Dfd, Dwd, occur only in eastern Siberia

This group climate is indicated by average temperatures below 10 °C throughout the year. This group is further divided into:

• Tundra climate, represented as ET, with warmest month has average temperature between 0 °C and 10 °C.
• Ice Cap climate, represented as EF, are average temperatures below 0 °C throughout the year.