Image of Ice Wind Chill Image of Ice

Wind Chill Calculator  |  New Wind Chill Chart  |  Old Wind Chill Chart

Wind Chill is the term used to describe the rate of heat loss on the human body resulting from the combined effect of low temperature and wind. As winds increase, heat is carried away from the body at a faster rate, driving down both the skin temperature and eventually the internal body temperature. While exposure to low wind chills can be life threatening to both humans and animals alike, the only effect that wind chill has on inanimate objects, such as vehicles, is that it shortens the time that it takes the object to cool to the actual air temperature (it cannot cool the object down below that temperature).

In November 2001, The National Weather Service implemented a new Wind Chill Temperature Index.  How does the old index compare with the new index?  In general, if given the same actual air temperature and wind...the new index will usually be warmer than what you would have expected with the old index. 

The first wind chill formula and tables were developed by Paul Allman Siple and Charles Passel working in the Antarctic before the Second World War, and were made available by the National Weather Service by the 1970s. It was based on the cooling rate of a small plastic bottle as its contents turned to ice while suspended in the wind on the expedition hut roof, at the same level as the anemometer. The so-called Windchill Index provided a pretty good indication of the severity of the weather.

In the 1960s, wind chill began to be reported as a wind chill equivalent temperature (WCET), which is theoretically less useful. The author of this change is unknown, but it was not Siple and Passel as is generally believed.[citation needed] At first, it was defined as the temperature at which the windchill index would be the same in the complete absence of wind. This led to equivalent temperatures that were obviously exaggerations of the severity of the weather. Charles Eagan realized that people are rarely still and that even when it was calm, there was some air movement. He redefined the absence of wind to be an air speed of 1.8 meters per second (4.0 mph), which was about as low a wind speed as a cup anemometer could measure. This led to more realistic (warmer-sounding) values of equivalent temperature.

We've created a Wind Chill Calculator below so you can compare the New Wind Chill Temperature Index with the Old Wind Chill Temperature Index.  You can also take a look at the New Wind Chill Chart with the Old Wind Chill Chart

Dress for Winter

What is the Wind Chill Now?
 

Air Temperature (ºF) =
Wind Speed (MPH) =
Old Wind Chill Index New Wind Chill Index

Note: Windchill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph. Bright sunshine may increase the wind chill temperature by 10 to 18 degrees F.


Here is how you calculate the Old Wind Chill Index:

Old Wind Chill T(wc)=.081 x (3.71 x sqrt(V) + 5.81 - 0.25 x V) x (T - 91.4) + 91.4 

Here is how you calculate the New Wind Chill Index:

New Wind Chill T(wc) = 35.74 + 0.6215T - 35.75(V0.16) + 0.4275T(V0.16)

where T(wc) is the Wind Chill in degrees F, V is the Wind Speed in MPH, and T is the temperature in degrees F.


New Wind Chill Chart
Temperature (F)
Wind (mph) Calm
40
35 30 25 20 15 10 5 0 -5 -10 -15 -20 -25 -30 -35 -40 -45
5
36
31 25 19 13 7 1 -5 -11 -16 -22 -28 -34 -40 -46 -52 -57 -63
10
34
27 21 15 9 3 -4 -10 -16 -22 -28 -35 -41 -47 -53 -59 -66 -72
15
32
25 19 13 6 0 -7 -13 -19 -26 -32 -39 -45 -51 -58 -64 -71 -77
20
30
24 17 11 4 -2 -9 -15 -22 -29 -35 -42 -48 -55 -61 -68 -74 -81
25
29
23 16 9 3 -4 -11 -17 -24 -31 -37 -44 -51 -58 -64 -71 -78 -84
30
28
22 15 8 1 -5 -12 -19 -26 -33 -39 -46 -53 -60 -67 -73 -80 -87
35
28
21 14 7 0 -7 -14 -21 -27 -34 -41 -48 -55 -62 -69 -76 -82 -89
40
27
20 13 6 -1 -8 -15 -22 -29 -36 -43 -50 -57 -64 -71 -78 -84 -91
45
26
19 12 5 -2 -9 -16 -23 -30 -37 -44 -51 -58 -65 -72 -79 -86 -93
50
26
19 12 4 -3 -10 -17 -24 -31 -38 -45 -52 -60 -67 -74 -81 -88 -95
55
25
18 11 4 -3 -11 -18 -25 -32 -39 -46 -54 -61 -68 -75 -82 -89 -97
60
25
17 10 3 -4 -11 -19 -26 -33 -40 -48 -55 -62 -69 -76 -84 -91 -98
Frostbite occurs in 15 minutes or less

 


Old Wind Chill Chart

Old Wind Chill Chart




Last modified August 16, 2001

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