metpy.calc.windchill(temperature, speed, face_level_winds=False, mask_undefined=True)[source]

Calculate the Wind Chill Temperature Index (WCTI).

Calculates WCTI from the current temperature and wind speed using the formula outlined by the FCM [FCMR192003].

Specifically, these formulas assume that wind speed is measured at 10m. If, instead, the speeds are measured at face level, the winds need to be multiplied by a factor of 1.5 (this can be done by specifying face_level_winds as True).

  • temperature (pint.Quantity) – Air temperature

  • speed (pint.Quantity) – Wind speed at 10m. If instead the winds are at face level, face_level_winds should be set to True and the 1.5 multiplicative correction will be applied automatically.

  • face_level_winds (bool, optional) – A flag indicating whether the wind speeds were measured at facial level instead of 10m, thus requiring a correction. Defaults to False.

  • mask_undefined (bool, optional) – A flag indicating whether a masked array should be returned with values where wind chill is undefined masked. These are values where the temperature > 50F or wind speed <= 3 miles per hour. Defaults to True.


pint.Quantity – Corresponding Wind Chill Temperature Index value(s)