National Weather Service Weather Forecast Office

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).

Beginning November 2001, the National Weather Service will be implementing 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 be warmer than what you would have expected with the old index.  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. 

	What is the Wind Chill Now?   Air Temperature (ºF) = Wind Speed (MPH) = Old Wind Chill Index New Wind Chill Index
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.

Temperature (F)
	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