Utility functions for calculating Wind Chill Index (WCI) and Wind Chill Temperature (WCT)

Calculate the Wind Chill Index (WCI) from air temperature and wind speed.

Wind Chill Index is derived from original work carried out by Gregorczuk [1]. It qualifies thermal sensations of a person in wintertime. It is especially useful at low and very low air temperature and at high wind speed.

Parameters
• ta – Air temperature [C]

• ws – Wind speed [m/s]

Returns

wci – Wind Chill Index [W/m2]

Get the category of effect associated with a given wind chill index (WCI).

Each number (from -4 to 3) represents a certain WCI thermal sensation category. With categories being the following:

• -4 = Extreme frost

• -3 = Frosty

• -2 = Cold

• -1 = Cool

• 0 = Comfortable

• 1 = Warm

• 2 = Hot

• 3 = Extremely hot

Parameters

wci – Wind Chill Index [W/m2]

Returns

category – An integer indicating the level of effect associated with the wind chill index. Values are one of the following:

• -4 = Extreme frost

• -3 = Frosty

• -2 = Cold

• -1 = Cool

• 0 = Comfortable

• 1 = Warm

• 2 = Hot

• 3 = Extremely hot

Calculate the Wind Chill Temperature (WCT) from air temperature and wind speed.

It is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. It’s used by both National Weather Service (NSW) in US and Canadian Meteorologist service. The formula is derived from Environment Canada [1].

Note

[1] “Environment Canada - Weather and Meteorology - Canada’s Wind Chill Index”. Ec.gc.ca. Retrieved 2013-08-09.

Parameters
• ta – Air temperature [C]

• ws – Wind speed [m/s]

Returns

twc – Wind Chill Temperature [C]

Get the category of effect associated with a given wind chill temperature (WCT).

Each number (from -6 to 0) represents a certain WCT thermal sensation category. With categories being the following:

• 0 = No discomfort. No risk of frostbite for most people.

• -1 = Slight increase in discomfort. Low risk of frostbite for most people

• -2 = Risk of hypothermia if outside for long periods without adequate protection. Low risk of frostbite for most people

• -3 = Risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold. Increasing risk of frostbite for most people in 10 to 30 minutes of exposure

• -4 = Risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold. High risk of frostbite for most people in 5 to 10 minutes of exposure

• -5 = Serious risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold. High risk of frostbite for most people in 2 to 5 minutes of exposure

• -6 = Danger! Outdoor conditions are hazardous. High risk of frostbite for most people in 2 minutes of exposure or less

Parameters

twc – Wind Chill Temperature [C]

Returns

category – An integer indicating the level of warning associated with the heat index. Values are one of the following:

• 0 = No discomfort

• -1 = Slight increase in discomfort

• -2 = Risk of hypothermia if outside for long periods without adequate protection

• -3 = Risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.

• -4 = Risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.

• -5 = Serious risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.

• -6 = Danger! Outdoor conditions are hazardous.