ck_winkler: Winkler Index
In climatekit: Unified Climate Indices for Temperature, Precipitation, and Drought

ck_winkler

R Documentation

Winkler Index

Description

The Winkler index (also called growing degree days for viticulture) accumulates daily mean temperature above 10 degrees C during the growing season (April-October in NH, October-April in SH).

Usage

ck_winkler(tavg, dates)

Arguments

`tavg`	Numeric vector of daily average temperatures (degrees C).
`dates`	Date vector of the same length as `tavg`.

Value

A data frame with columns period, value, index, and unit.

References

Amerine, M. A., & Winkler, A. J. (1944). Composition and quality of musts and wines of California grapes.

Examples

dates <- seq(as.Date("2024-04-01"), as.Date("2024-10-31"), by = "day")
set.seed(42)
tavg <- rnorm(length(dates), mean = 18, sd = 4)
ck_winkler(tavg, dates)

climatekit documentation built on May 9, 2026, 5:08 p.m.