Wind chill is an indication of quickly your body will lose heat. It is determined by the actual temperature and wind speed, which both cause body heat loss. For instance, when the actual temperature is 35° Fahrenheit and there is a 10-mph wind, the body loses heat at the rate it would if the temperature was 22° and there was no wind.
 

Wind Chill
Air Temp (°F)	Wind Speed (mph)
	0	5	10	15	20	25	30	35	40	45
35°	35	33	22	16	12	8	6	4	3	2
30°	30	27	16	9	4	1	-2	-4	-5	-6
25°	25	21	10	2	-3	-7	-10	-12	-13	-14
20°	20	16	3	-5	-10	-15	-18	-20	-21	-22
15°	15	12	-3	-11	-17	-22	-25	-27	-29	-30
10°	10	7	-9	-18	-24	-29	-33	-35	-37	-38
5°	5	0	-15	-25	-31	-36	-41	-43	-45	-46
0°	0	-5	-22	-31	-39	-44	-49	-52	-53	-54
-5°	-5	-10	-27	-38	-46	-51	-56	-58	-60	-62
-10°	-10	-15	-34	-45	-53	-59	-64	-67	-69	-70
-15°	-15	-21	-40	-51	-60	-66	-71	-74	-76	-78

 

		=	Great danger of exposed skin freezing
		=	Danger of exposed skin freezing
		=	Little danger if properly dressed

 
For more information on cold weather dangers and how to recognize and treat them, check Princeton's Guide to Hypothermia And Cold Weather Injuries.