Aristotle's Climate Classification

Annual Cycle of global temperature

Annual Cycle of global precipitation

Annual Cycle of global precipitation minus evaporation

Annual Cycle of global soil moisture

Map Using Koppen's Climate Classification

General Steps for Determining Koppen Climate Type

1. Determine whether a Climate is arid/semiarid (B climates).

2. If not a B climate, identify the climate as A, C, D, or E according to temperature data.

3. After identifying A, BS, BW, C, D, or E, determine additional letters for subcategories.

4. For C and D climates, determine a third letter:

Detailed Procedure for Determining Koppen Climate Type

1. Determine whether a Climate is arid/semiarid (B climates)

a. Determine annual rainfall in mm and annual average temperature in ^oC

b. If r > 20(t+14) it is not a B climate. Go to Step 2

c. Determine seasonality of rainfall. Then determine BS, BW or neither according to the criteria below:

	Rainfall Distribution	Not a B climate Go to Step 2	BS (Semi-arid)	BW (Arid)
	70% of rainfall in warmest 6 months	r > 20(t+14)	10(t+14)<r<20(t+14)	r<10(t+14)
	70% of rainfall in coldest 6 months	r > 20t	10t<r<20t	r<10t
	Even rainfall distribution (neither of above)	r > 20(t+7)	10(t+7)<r<20(t+7)	r<10(t+7)

d. For BS or BW, go to Step 3.

2. If not a B climate, identify the climate as A, C, D, or E according to temperature data

a. Temperature of coldest month > 18 ^oC, it is an A climate.

b. Temperature of coldest month in -3 ^oC to 18 ^oC range, Warmest month > 10 ^oC, it is a C climate.

c. Temperature of coldest month < -3 ^oC, Warmest month > 10 ^oC, it is a D climate.

d. Warmest month < 10 ^oC, it is a E climate.

3. After identifying A, BS, BW, C, D, or E, determine additional letters for subcategories.

A climates:
Af : Rainfall in driest month at least 60mm

Am: Rainfall in driest month less than 60mm, but > 100 - (annual rainfall/25)

Aw: Not Af or Am

B climates:

BSh or BWh: average annual temp. >18 ^oC

BSk or BWk: average annual temp. <18 ^oC

C climates:
Cw: at least 10 times as much precip. in wettest summer month as in driest winter month.

Cs: at least 3 times as much precip. in wettest winter month as in driest summer month.

Cf: Not Cw or Cs

See step 4 below.

D climates:
Dw: at least 10 times as much precip. in wettest summer month as in driest winter month.

Ds: at least 3 times as much precip. in wettest winter month as in driest summer month.

Df: Not Dw or Ds

See step 4 below.

E climates:
ET: warmest month in 0 - 10 ^oC range

EF: warmest month below 0 ^oC

4. For C and D climates, determine a third letter:
a (e.g. Cfa) : warmest month > 22 ^oC

b (e.g. Dsb): warmest month < 22 ^oC; at least 4 months > 10 ^oC

c (e.g. Cfc) : warmest month < 22 ^oC; 1-3 months > 10 ^oC

d (e.g. Dwd): coldest month < -38 ^oC

Koppen Climates and Biomes