Köppen-Trewartha Classification

Definition of types and subtypes as defined by the Köppen-Trewartha climate classification according to Trewartha and Horn (1980). T denotes mean annual temperature (°C), Pmean is the mean annual rainfall (cm), R is Patton’s precipitation threshold. Tcold (Twarm) stands for monthly mean air temperature of the coldest (warmest) month

Type Criteria Subtype Rainfall regime
A Tcold > 18 °C
Pmean above value given in B
Ar 10 to 12 months wet; 0 to 2 months dry
Aw winter (low-sun period) dry; more than 2 months dry
As summer (high-sun period) dry; rare in A climates
B Pmean < R (R = 2.3T - 0.64 Pw +41) BS R/2 < Pmean < R
BW Pmean < R/2
C 8-12 months with T > 10 °C Cs summer dry; at least three times as much rain in winter half year as in summer half year; driest summer month less than 3 cm of precipitation; annual precipitation total under 89 cm
Cw winter dry; at least ten times as much rain in summer half year as in winter half year
Cf no dry season; difference between driest and wettest month less than required for s and w; driest month of summer more than 3 cm
D 4-7 months with T > 10 °C Do Tcold > 0 °C (to 2 °C in some locations inland). In present study the limit is 0 °C.
Dc Tcold < 0 °C (to 2 °C). In present study the limit is 0 °C.
E 1-3 months with T > 10 °C -
F Twarm < 10 °C Ft Twarm > 0 °C
Fi Twarm < 0 °C