At what temperature does wind chill apply?

The NWS formula is only defined at 50°F (10°C) and colder, with wind of at least 3 mph. Above 50°F, wind still makes you feel cooler, but the formula is not designed for it and the official wind chill is not reported.

Can wind chill freeze water above 32°F?

No. Wind chill describes how fast heat is lost from warm skin, not a temperature objects can fall to. Water, pipes and car engines cool faster in wind, but not below the actual air temperature.

What wind speed should I use?

The sustained wind from your forecast or observation, which is measured at 10 m above the ground. Gusts give a lower, briefer wind chill and are not what the formula was designed around.

Why is this different from the old wind chill chart?

Before November 2001, North America used an index from the 1940s that made the wind feel much colder than it does. The current formula comes from modern human trials and heat-transfer modeling, and is what NWS and Environment Canada publish today.

Does the sun change the wind chill?

The formula assumes no sun. Bright sunshine can make conditions feel noticeably warmer than the wind chill suggests, though the NWS index itself does not adjust for it.

Cold exposure · NWS 2001 formula

Wind Chill Calculator

Wind chill estimates how cold exposed skin feels when wind strips heat away faster than still air would. Enter the air temperature and the wind speed from your forecast.

Formula

WC = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16
T = air temperature in °F, V = wind speed in mph (measured at 10 m).

Source: National Weather Service and Meteorological Service of Canada wind chill temperature index, introduced November 2001.

Valid range

Defined only for air temperatures of 50°F (10°C) or colder and wind of at least 3 mph (about 5 km/h). Outside that range there is no wind chill, and the calculator shows the air temperature with a note instead.
The formula assumes a person walking at about 3 mph into the wind, at night, with a bare face. Sunshine can make it feel several degrees warmer than the number.

What wind chill means

Skin is warmed by a thin layer of still air next to it. Wind strips that layer away, so exposed skin loses heat faster, and it feels colder than the thermometer reads. Wind chill expresses that faster heat loss as the temperature that would feel the same in light wind.

Wind chill does not cool objects below the air temperature. A car radiator or a water pipe cools faster in wind, but it never gets colder than the air itself. It matters for people and animals because of frostbite and hypothermia risk.

The 2001 formula replaced the older Siple and Passel index from the 1940s, which overstated the chill. It uses wind at 10 m, the height of standard weather station anemometers, reduced to face height inside the model.

Wind chill chart (°F, wind in mph)

Generated from the same equation as the calculator above.

Wind chill chart (°F, wind in mph)
Wind (mph) / Temperature (°F)	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

Wind chill chart (°C, wind in km/h)

Generated from the same equation as the calculator above.

Wind chill chart (°C, wind in km/h)
Wind (km/h) / Temperature (°C)	10°	5°	0°	−5°	−10°	−15°	−20°	−25°	−30°	−35°	−40°
10	9	3	−3	−9	−15	−21	−27	−33	−39	−45	−51
20	7	1	−5	−12	−18	−24	−30	−37	−43	−49	−56
30	7	0	−6	−13	−19	−26	−33	−39	−46	−52	−59
40	6	−1	−7	−14	−21	−27	−34	−41	−47	−54	−61
50	6	−1	−8	−15	−22	−29	−35	−42	−49	−56	−63
60	5	−2	−9	−16	−23	−30	−36	−43	−50	−57	−64
70	5	−2	−9	−16	−23	−30	−37	−44	−51	−58	−65
80	4	−3	−10	−17	−24	−31	−38	−45	−52	−59	−67

Wind chill questions

At what temperature does wind chill apply?: The NWS formula is only defined at 50°F (10°C) and colder, with wind of at least 3 mph. Above 50°F, wind still makes you feel cooler, but the formula is not designed for it and the official wind chill is not reported.
Can wind chill freeze water above 32°F?: No. Wind chill describes how fast heat is lost from warm skin, not a temperature objects can fall to. Water, pipes and car engines cool faster in wind, but not below the actual air temperature.
What wind speed should I use?: The sustained wind from your forecast or observation, which is measured at 10 m above the ground. Gusts give a lower, briefer wind chill and are not what the formula was designed around.
Why is this different from the old wind chill chart?: Before November 2001, North America used an index from the 1940s that made the wind feel much colder than it does. The current formula comes from modern human trials and heat-transfer modeling, and is what NWS and Environment Canada publish today.
Does the sun change the wind chill?: The formula assumes no sun. Bright sunshine can make conditions feel noticeably warmer than the wind chill suggests, though the NWS index itself does not adjust for it.

Wind Chill Calculator