Examples · 1991–2020

Station: Buenos Aires Observatorio. Data source

Monthly data

Paste 12 rows (months) or 2 rows of 12 values (T and P). Separate columns with tabs or semicolons.

Monthly normals: mean temperature in degrees Celsius and precipitation in millimetres. The footer shows mean T and total P.
Month	T (°C)	P (mm)
January
February
March
April
May
June
July
August
September
October
November
December
Year	Mean (MAT)18.08	Total (MAP)1258

Summer: October–March.

Enter or ↓: next month. ↑: previous month.

Boundary between temperate (C) and cold (D) climates

Compared with the mean temperature of the coldest month.

Classification

Cfa

Humid temperate, hot summer

View all 30 classes

Why

C Temperate: MAP 1258 ≥ 10·Pthreshold = 501.7 mmThot 24.90 > 10 °CTcold 11.00 < 18 °CTcold 11.00 > 0 °C; The warmest month exceeds 10 °C; the coldest is above the C/D boundary but below 18 °C.
f No dry season: Psdry 117.6 ≥ 40 mmPsdry 117.6 ≥ Pwwet/3 = 43.43 mmPwdry 61.50 ≥ Pswet/10 = 13.44 mm; Neither the dry-summer nor the dry-winter criteria are met.
a Hot summer: Thot 24.90 ≥ 22 °C; The warmest month reaches 22 °C.

Climograph

Mean temperature (°C)Precipitation (mm)Dry · P ≤ 2T

Scale: 20 mm of precipitation corresponds to 10 °C of temperature.

Dry months: none.

Climate variables

MAT Mean annual temperature: 18.08 °C
MAP Annual precipitation: 1258 mm
Tcold Coldest-month temperature: 11.00 °CJul
Thot Warmest-month temperature: 24.90 °CJan
Tmon10 Months with T > 10 °C: 12 months
Ps Summer precipitation: 747.0 mm
Pw Winter precipitation: 510.6 mm
Pthreshold Aridity threshold coefficient: 50.17 Distributed rainfall: 2·MAT + 14
Pdry Driest month of the year: 61.50 mmJun
Psdry Driest summer month: 117.6 mmNov
Pswet Wettest summer month: 134.4 mmJan
Pwdry Driest winter month: 61.50 mmJun
Pwwet Wettest winter month: 130.3 mmApr
Summer half-year: October–March
Precipitation in summer: 59.40 %

Fundamentals & Explanation

What Köppen classifies

Köppen–Geiger classifies climates by temperature and precipitation. The 30 classes follow Beck et al. (2023, Table 1), based on Peel et al. (2007).

For each month, T is the average of daily mean temperatures and P is accumulated precipitation. Their averages over 30 years are called climatological normals. A single year describes that year but does not represent the location’s climate.

Preparing the data

You can paste one column of 12 values, two T/P columns or two T/P rows. Without labels, complete series run from January to December.
Copy only mean temperature and precipitation. Month labels are optional; labelled annual totals are omitted.
Either decimal commas or points are accepted, without thousands separators. Leave a cell empty for missing data; zero does not mean missing.

First letter: aridity takes precedence

MAT is the average of the twelve temperatures and MAP is the sum of the twelve precipitation values. Tcold and Thot are the mean temperatures of the coldest and warmest months. B (arid) is evaluated first; otherwise:

A (tropical): the coldest month reaches 18 °C.
E (polar): the warmest month does not exceed 10 °C.
C (temperate) and D (cold): the warmest month exceeds 10 °C and the coldest is below 18 °C. C lies above the chosen boundary; D lies at or below it.

The aridity threshold and 70%

The warmer half-year, April–September or October–March, is summer; a tie selects October–March. Ps and Pw are summer and winter precipitation totals.

Pthreshold = 2·MAT + c
c = 0 if Pw > 0.7·MAP
c = 28 if Ps > 0.7·MAP
c = 14 otherwise

B requires MAP < 10·Pthreshold. Within B, W (desert) requires MAP < 5·Pthreshold; otherwise it is S (steppe). The letter h means MAT ≥ 18 °C; k means MAT < 18 °C. Pthreshold is a coefficient: multiplying it by 10 gives the annual threshold in mm.

Exactly 70% belongs to the distributed-rainfall case, with c = 14.

Rainfall and temperature letters

Pdry is precipitation in the driest month of the year. Psdry and Pswet are the lowest and highest monthly precipitation totals in summer; Pwdry and Pwwet are their winter equivalents.

Within A, f requires the driest month to reach 60 mm; otherwise m requires Pdry ≥ 100 − MAP/25, and the remainder is w. This table groups savannah climates as Aw and does not distinguish As.

Within C and D, s requires both Psdry < 40 mm and 3·Psdry < Pwwet. The letter w requires 10·Pwdry < Pswet. If both apply, w is selected when Ps > Pw, and s otherwise. If neither applies, the letter is f.

Tmon10 counts the months above 10 °C. The third letter is a if Thot ≥ 22 °C; otherwise b when Tmon10 ≥ 4. One to three months gives c, except in D with Tcold < −38 °C, which gives d. Within E, T means Thot > 0 °C and F means Thot ≤ 0 °C.

0 °C or −3 °C

The 0 °C boundary follows Beck and Peel. The −3 °C boundary is another convention for separating C from D. The coldest month must exceed the boundary for C; at or below it, the group is D.

The choice changes only this boundary; the other rules follow Beck. It therefore differs from the full criteria of Kottek et al. (2006). In the examples, Seoul changes from Dwa to Cwa with −3 °C; B climates are unaffected.

Reading the climograph

Bars show P and the red line shows T. The scales maintain a ratio of 20 mm to 10 °C, with aligned zeros. A dry month satisfies P ≤ 2T (Bagnouls and Gaussen, 1957) and is marked in amber.

Monthly dryness is distinct from Köppen’s s and w letters. The precipitation scale is linear, without the compression above 100 mm used in a Walter–Lieth diagram; in very rainy climates, this places the temperature curve near the bottom.

Interpretation and limits

Nearby stations and maps may give different classes because of location, elevation, period or criteria.
Notices flag proximity to a boundary: 0.5 °C, 5% of a precipitation threshold, or 2 percentage points around 70%. The 70% notice appears if switching rainfall cases would change the class. A notice also appears if the half-years differ by at most 0.5 °C and choosing the other as summer changes the class. These notices do not quantify uncertainty in the data.
The class is determined before rounding. Expand decimals lets you view more digits; very close values may still look equal.
The climate class alone does not determine vegetation or available water. Another bioclimatic approach is Holdridge life zones.

References and data

Beck et al. (2023). Classification criteria, Table 1, and legend colors.
Peel, Finlayson and McMahon (2007). Basis of the Beck criteria.
Kottek et al. (2006). Another Köppen–Geiger convention.
Bagnouls and Gaussen (1957), p. 194. Dry-month criterion.
World Meteorological Organization (2017). Guidelines on the Calculation of Climate Normals, No. 1203.
Station data: WMO / NCEI. 1991–2020 averages. Series cover at least 24 years; NCEI assumes 30 when a country does not report the count. Worldwide files: temperatures (CSV) and precipitation (CSV).

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Colors of the Köppen classes

Palette from Beck et al. (2023).

A · Tropical
Class	Description
Af	Tropical rainforest
Am	Tropical monsoon
Aw	Tropical savannah

B · Arid
Class	Description
BWh	Hot desert
BWk	Cold desert
BSh	Hot semi-arid
BSk	Cold semi-arid

C · Temperate
Class	Description
Csa	Temperate, dry and hot summer
Csb	Temperate, dry and warm summer
Csc	Temperate, dry and cool summer
Cwa	Temperate, dry winter and hot summer
Cwb	Temperate, dry winter and warm summer
Cwc	Temperate, dry winter and cool summer
Cfa	Humid temperate, hot summer
Cfb	Humid temperate, warm summer
Cfc	Humid temperate, cool summer

D · Cold
Class	Description
Dsa	Cold, dry and hot summer
Dsb	Cold, dry and warm summer
Dsc	Cold, dry and cool summer
Dsd	Cold, dry summer and extreme winter
Dwa	Cold, dry winter and hot summer
Dwb	Cold, dry winter and warm summer
Dwc	Cold, dry winter and cool summer
Dwd	Dry, extremely cold winter
Dfa	Humid cold, hot summer
Dfb	Humid cold, warm summer
Dfc	Humid cold, cool summer
Dfd	Humid cold, extreme winter

E · Polar
Class	Description
ET	Polar tundra
EF	Polar ice cap

Köppen climate classification and climograph

Classification

Humid temperate, hot summer

Why

Climograph

Fundamentals & Explanation

What Köppen classifies

Preparing the data

First letter: aridity takes precedence

The aridity threshold and 70%

Rainfall and temperature letters

0 °C or −3 °C

Reading the climograph

Interpretation and limits

References and data

Colors of the Köppen classes

What Köppen classifies

Preparing the data

First letter: aridity takes precedence

The aridity threshold and 70%

Rainfall and temperature letters

0 °C or −3 °C

Reading the climograph

Interpretation and limits

References and data