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Wind Chill

The wind chill index is, quite simply, a measure of the rate of heat loss. As anyone with experience in cold winter climates can attest, temperature is just one of several factors that determine outdoor comfort. Precipitation, sunlight, and wind all play important roles. The wind chill table below takes into account both temperature and wind speed.

The original work on wind chill was done by Antarctic explorers Paul Siple and Charles Passel in the winter of 1941 by measuring the amount of time it took a pan of water to freeze. They found that the rate of heat loss from the container could be determined from the air temperature and wind speed. There is some controversy over this methodology because its application to humans is not straightforward. Humans are more complex than a pan of water and respond differently depending on age, size, health, degree of physical activity, etc. However, the wind chill index can still be a useful rule-of-thumb for making decisions about outdoor activities.

Wind speed (knots)	Temperature (degrees Fahrenheit)
0	40	35	30	25	20	15	10	5	0	-5	-10	-15	-20	-25	-30
5	36	30	25	19	14	8	3	-2	-8	-13	-19	-24	-30	-35	-40
10	26	20	13	7	1	-6	-12	-18	-25	-31	-37	-44	-50	-56	-63
15	20	13	6	-1	-7	-14	-21	-28	-35	-42	-49	-56	-63	-70	-77
20	16	9	2	-6	-13	-20	-28	-35	-42	-50	-57	-64	-72	-79	-86
25	13	6	-2	-9	-17	-25	-32	-40	-47	-55	-63	-70	-78	-85	-93
30	11	4	-4	-12	-20	-28	-35	-43	-51	-59	-66	-74	-82	-90	-98
35	10	2	-6	-14	-22	-30	-37	-45	-53	-61	-69	-77	-85	-93	-101
40	9	1	-7	-15	-23	-31	-39	-47	-55	-63	-71	-79	-87	-95	-103

Wind Chill Possible Effects

30°F or greater Chilly: Generally unpleasant

15°F to 30°F Cold: Unpleasant

0°F to 15°F Very Cold: Very unpleasant

-20°F to 0°F Bitter Cold: Frostbite possible

-20°F to -60°F Extremely Cold: Frostbite likely. Outdoor activity becomes dangerous

-60°F or less Frigidly Cold: Exposed flesh will freeze within half a minute

Document last modified on Friday, 19-Jan-2007 07:18:32 MST.