NWS Birmingham, AL - Wind Chill


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Wind Chill

The Wind Chill/Temperature Index will make use of advances in meteorology, biometeorology and computer modeling to provide a more accurate, useful formula for calculating the dangers from winter winds and freezing temperatures. In addition, clinical trials have been conducted and the results of those trials have been used to verify and improve the accuracy of the new formula.

Led by the NWS, implementation of the standardized WCT Index will take place throughout the nation and will involve the entire meteorological community and the media - which will play an important role in explaining the index to the general public. In this way, an accurate and consistent measure will be provided to help the public protect itself against the dangers of frostbite and hypothermia. The index will be implemented in Canada and the United States in order to have a consistent WCT Index for North America.

Specifically, the WCT index:

uses calculated wind speed at an average height of five feet (typical height of a human face) based on readings from the national standard height of 33 feet (typical height of an anemometer);
is based on the latest heat transfer theory, i.e., heat loss from the body to its surroundings, during cold and breezy/windy days;
uses a standard factor for skin tissue and assumes a no sunlight scenario

The new equation,
Wind Chill (^oF) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)

Where, T = Air Temperature (^oF)
V = Wind Speed (mph)

Temperature (F)

W
i
n
d

S
p
e
e
d

MPH

Calm

-5

-10

-15

-20

-25

-30

-35

-40

-45

-5

-11

-16

-22

-28

-34

-40

-46

-52

-57

-63

-4

-10

-16

-22

-28

-35

-41

-47

-53

-59

-66

-72

-7

-13

-19

-26

-32

-39

-45

-51

-58

-64

-71

-77

-2

-9

-15

-22

-29

-35

-42

-48

-55

-61

-68

-74

-81

-4

-11

-17

-24

-31

-37

-44

-51

-58

-64

-71

-78

-84

-5

-12

-19

-26

-33

-39

-46

-53

-60

-67

-73

-80

-87

-7

-14

-21

-27

-34

-41

-48

-55

-62

-69

-76

-82

-89

-1

-8

-15

-22

-29

-36

-43

-50

-57

-64

-71

-78

-84

-91

-2

-9

-16

-23

-30

-37

-44

-51

-58

-65

-72

-79

-86

-93

-3

-10

-17

-24

-31

-38

-45

-52

-60

-67

-74

-81

-88

-95

-3

-11

-18

-25

-32

-39

-46

-54

-61

-68

-75

-82

-89

-97

-4

-11

-19

-26

-33

-40

-48

-55

-62

-69

-76

-84

-91

-98

Frostbite occurs in 15 minutes or less

Wind Chill/Temperature Index Calculation

Enter in the air temperature ( T_air ) in degrees Fahrenheit and wind speed in mile per hour ( mph ), then click on the Calculate WC to compute the windchill ( WC ).
T_air^o F		mph

A chart showing a comparison between the old and new calculation;

A chart showing a comparison between the old and the new calculation.

Back to the Meteorological Calculator

Wind Chill

Questions or comments about this page? Send to Ron Murphy Posted 08.18.2001

Questions or comments about this page? Send to Ron Murphy

Posted 08.18.2001