Koppen Climate Class Classifier

Köppen–Geiger classification of twelve homogeneous monthly normals with the 0°C temperate/continental boundary and aridity tested first. Northern summer is April–September, reversed in the south. If both dry-season rules apply, s takes priority; tropical dry-season ties use the first driest month. Not a mapped climate identity, crop recommendation or forecast.

Description

A Köppen-style classifier uses monthly temperature and precipitation normals and a hemisphere convention.

A Köppen-style classifier uses monthly temperature and precipitation normals and a hemisphere convention.^[1]

Different threshold editions can change boundary classifications, so this implementation's rules matter. Use Koppen Climate Class Classifier to evaluate the supplied inputs under the model explained below.

When to use Koppen Climate Class Classifier

Use Koppen Climate Class Classifier to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.

How to use Koppen Climate Class Classifier and understand its results

Establish the units, measurement scope and model assumptions before entering values.
Enter Monthly temperature c, Monthly precipitation mm, Northern hemisphere using the field table and validation rules below, then run the tool.
Read Koppen code, Annual temperature c, Annual precipitation mm, Dry climate threshold mm; interpret the units, signs, ordering and unknown-value placeholders described below.
Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.

Input field	Meaning	Value type	Requirement
monthlyTemperatureC	Monthly temperature c	array of number	Required; constraints below
monthlyPrecipitationMm	Monthly precipitation mm	array of number	Required; constraints below
northernHemisphere	Northern hemisphere	boolean	Required; constraints below

Enter twelve January–December finite temperature normals in °C and nonnegative precipitation normals in mm and a hemisphere flag. Summer is April–September in the north and October–March in the south. Annual dry threshold is 20×meanTemperature plus 280 for at least 70 percent summer rain, 0 for at most 30 percent and 140 otherwise; zero rain uses a 50 percent share. Apply dryness first: below threshold gives BW below half-threshold or BS otherwise, with h at mean≥18 and k below. Then hottest month below 10 gives ET if at least 0 or EF below. If coldest≥18, use Af for driest rain≥60, Am for rain≥100−annualRain/25, otherwise As when the first driest month is in summer and Aw otherwise. Remaining climates use C for coldest>0 and D otherwise; s requires summer minimum<40 and below winter maximum/3, else w requires winter minimum below summer maximum/10, else f. Thermal suffix a requires hottest≥22, else b requires at least four months≥10, else d requires D and coldest<−38, else c. Ties for driest month use its first January–December occurrence. This explicit variant is not every Köppen edition or an official climate dataset.

dryThreshold=20×Tmean+seasonalOffset; branch order=B→E→A→C/D; exact subclass thresholds described above

Use the field order, units and branch conditions described above.

Output field	Meaning	Value type
koppenCode	Koppen code	string
annualTemperatureC	Annual temperature c	number
annualPrecipitationMm	Annual precipitation mm	number
dryClimateThresholdMm	Dry climate threshold mm	number

json

{
  "input": {
    "monthlyTemperatureC": [
      25,
      25,
      25,
      25,
      25,
      25,
      25,
      25,
      25,
      25,
      25,
      25
    ],
    "monthlyPrecipitationMm": [
      100,
      100,
      100,
      100,
      100,
      100,
      100,
      100,
      100,
      100,
      100,
      100
    ],
    "northernHemisphere": true
  },
  "output": {
    "koppenCode": "Af",
    "annualTemperatureC": 25,
    "annualPrecipitationMm": 1200,
    "dryClimateThresholdMm": 640
  }
}

Limitations and assumptions

Different threshold editions can change boundary classifications, so this implementation's rules matter. Apply the exact scope and assumptions explained above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.

Alternative or Complementary methods

Use Trewartha Climate Classifier for a related task: Trewartha-style groups combine temperature seasonality with an aridity criterion.

Use Koppen Subclass Letter Resolver for a related task: A Köppen code contains group and subclass symbols with group-specific meanings.

References

Koppen Climate Class Classifier — tool.io

Similar or alternative tools

Trewartha Climate Classifier
Trewartha-style groups combine temperature seasonality with an aridity criterion.
Koppen Subclass Letter Resolver
A Köppen code contains group and subclass symbols with group-specific meanings.