Wind chill chart in °F and °C, with frostbite risk

At 0 °F in a 15 mph wind the NWS wind chill is −19 °F; at −20 °C and 30 km/h Environment Canada gives −33 °C, High risk: any exposed skin can freeze in 10 to 30 minutes. The two services’ formulas differ by at most 0.056 °C across the 176 metric cells, yet 4 round a degree apart.

Line chart of the NWS wind chill against wind speed from 5 to 60 mph at three air temperatures. At 20 °F air it falls from 13 °F at 5 mph to −4 °F at 60 mph; at 0 °F air it falls from −11 °F at 5 mph to −33 °F at 60 mph; at −20 °F air it falls from −34 °F at 5 mph to −62 °F at 60 mph. Hatched bands mark Environment Canada’s high level (−17.5 to −39.1 °F), very high level (−39.1 to −53.5 °F) and severe level (−53.5 to −66.1 °F). A dashed line marks 50 km/h (31.1 mph), above which frostbite can come faster. — At 0 °F air the wind chill reaches −19 °F by 15 mph and only −33 °F by 60 mph: the formula raises the wind speed to the power 0.16, so each extra mph lowers the wind chill less than the one before. Every plotted point is a row of the table. Image © ScienceQuest, CC BY 4.0: free to reuse with credit and a link to this page, as the image licence explains.

Chart data: wind chill at 20, 0 and −20 °F

NWS wind chill to a tenth of a °F at 20 °F, 0 °F and −20 °F air, every 5 mph: each row is one set of points on the chart
Wind (mph)	Air temperature
Wind (mph)	20	0	−20
5	13.0	−10.5	−34.0
10	8.9	−15.9	−40.7
15	6.2	−19.4	−45.0
20	4.2	−22.0	−48.2
25	2.6	−24.1	−50.8
30	1.3	−25.9	−53.0
35	0.1	−27.4	−54.9
40	−0.9	−28.8	−56.6
45	−1.8	−30.0	−58.1
50	−2.7	−31.1	−59.5
55	−3.5	−32.1	−60.8
60	−4.2	−33.1	−62.0

Wind chill chart in °F and mph (NWS formula)

NWS wind chill in whole °F for air from 40 °F down to −45 °F and wind from 5 to 60 mph, wind measured at 33 ft (10 m)
Wind (mph)	Air temperature (°F)
Wind (mph)	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

Each cell is the NWS formula rounded to a whole °F, and all 216 match the NWS’s printed chart, effective 1 November 2001 [2]. The NWS defines wind chill only at or below 50 °F with a wind above 3 mph.

Wind chill chart in °C and km/h, with risk levels (Environment Canada)

Environment Canada wind chill in whole °C, each with its risk level, for air from 0 °C down to −50 °C and wind from 5 to 80 km/h at 10 m
Wind (km/h)	Air temperature (°C)
Wind (km/h)	0	−5	−10	−15	−20	−25	−30	−35	−40	−45	−50
5	−2 L	−7 L	−13 M	−19 M	−24 M	−30 H	−36 H	−41 VH	−47 VH	−53 S	−58 E
10	−3 L	−9 L	−15 M	−21 M	−27 M	−33 H	−39 H	−45 VH	−51 S	−57 E	−63 E
15	−4 L	−11 M	−17 M	−23 M	−29 H	−35 H	−41 VH	−48 S	−54 S	−60 E	−66 E
20	−5 L	−12 M	−18 M	−24 M	−30 H	−37 H	−43 VH	−49 S	−56 E	−62 E	−68 E
25	−6 L	−12 M	−19 M	−25 M	−32 H	−38 H	−44 VH	−51 S	−57 E	−64 E	−70 E
30	−6 L	−13 M	−20 M	−26 M	−33 H	−39 H	−46 VH	−52 S	−59 E	−65 E	−72 E
35	−7 L	−14 M	−20 M	−27 M	−33 H	−40 VH	−47 VH	−53 S	−60 E	−66 E	−73 E
40	−7 L	−14 M	−21 M	−27 M	−34 H	−41 VH	−48 S	−54 S	−61 E	−68 E	−74 E
45	−8 L	−15 M	−21 M	−28 H	−35 H	−42 VH	−48 S	−55 E	−62 E	−69 E	−75 E
50	−8 L	−15 M	−22 M	−29 H	−35 H	−42 VH	−49 S	−56 E	−63 E	−69 E	−76 E
55	−8 L	−15 M	−22 M	−29 H	−36 H	−43 VH	−50 S	−57 E	−63 E	−70 E	−77 E
60	−9 L	−16 M	−23 M	−30 H	−36 H	−43 VH	−50 S	−57 E	−64 E	−71 E	−78 E
65	−9 L	−16 M	−23 M	−30 H	−37 H	−44 VH	−51 S	−58 E	−65 E	−72 E	−79 E
70	−9 L	−16 M	−23 M	−30 H	−37 H	−44 VH	−51 S	−58 E	−65 E	−72 E	−80 E
75	−10 M	−17 M	−24 M	−31 H	−38 H	−45 VH	−52 S	−59 E	−66 E	−73 E	−80 E
80	−10 M	−17 M	−24 M	−31 H	−38 H	−45 VH	−52 S	−60 E	−67 E	−74 E	−81 E

The letters are the risk levels in the key below: L low, M moderate, H high, VH very high, S severe, E extreme. Environment Canada’s printed chart gives −45 at −30 °C and 30 km/h; its formula gives −45.6, which rounds to −46, as here. Its other 65 printed cells match this table [6].

Frostbite risk levels

Environment Canada’s wind chill risk levels by the wind chill in whole °C, with the whole °F wind chills that fall in each level
Risk level	In the chart	Wind chill °C	Wind chill, rounded °F	What Environment Canada says happens
Low	L	0 to −9	32 to 15	Slight increase in physical discomfort
Moderate	M	−10 to −27	14 to −17	Risk of hypothermia and frostbite if outdoors for long periods of time without adequate protection
High	H	−28 to −39	−18 to −39	Any exposed skin can freeze in 10 to 30 minutes
Very high	VH	−40 to −47	−40 to −53	Any exposed skin can freeze in 5 to 10 minutes
Severe	S	−48 to −54	−54 to −66	Exposed skin can freeze in 2 to 5 minutes
Extreme	E	−55 or colder	−67 or colder	Exposed skin can freeze in less than 2 minutes

Environment Canada adds that in sustained winds over 50 km/h (31 mph), frostbite can occur faster than these times.

The risk levels are a guide for planning time outdoors. Follow any cold weather warning the NWS or Environment Canada issues for your area.

Why the formulas disagree

The NWS chart took effect on 1 November 2001 [2], and Environment Canada prints the same index in °C and km/h [5]. Osczevski and Bluestein (2005) describe the model behind both, the heat lost from the upwind side of a head-sized cylinder walking into the wind [4]. Both forms share the 0.6215 term and the 0.16 power. Neither is the other converted: the NWS’s 35.74, 35.75 and 0.4275, converted exactly to °C and km/h, become 13.127, 11.362 and 0.39616, and Environment Canada prints 13.12, 11.37 and 0.3965. That puts the two up to 0.056 °C apart on the metric chart, about 7 times the 0.008 °C that rounding the converted set to four figures would leave.

Each service rounds its wind chill to a whole degree in its own unit. At −10 °C and 30 km/h the NWS form gives −19.49 °C and Environment Canada’s −19.52 °C, so one rounds to −19 and the other to −20. That happens in 4 of the 176 metric cells. At −30 °C and 40 km/h, Environment Canada’s own worked example, the split crosses a risk level: the NWS form gives −47.465 °C, which rounds to −47, Very high risk, and Environment Canada’s gives −47.504 °C, which rounds to −48, Severe risk [6].

The NWS defines wind chill at or below 50 °F with a wind above 3 mph [1]. Environment Canada shows it only at 0 °C or colder, and below 5 km/h it switches to a light wind formula [5], which the metric table does not need because its rows start at 5 km/h. The NWS shades its printed chart at 30, 10 and 5 minutes to frostbite [2]; the levels in these tables are Environment Canada’s [6].

The formulas

NWS wind chill (T in °F, V in mph at 33 ft) [1]: $\mathrm{WCT} = 35.74 + 0.6215\,T - 35.75\,V^{0.16} + 0.4275\,T\,V^{0.16}$
Environment Canada wind chill, formula 1 (T in °C, V in km/h at 10 m) [5]: $W = 13.12 + 0.6215\,T - 11.37\,V^{0.16} + 0.3965\,T\,V^{0.16}$

Where each formula holds

Each formula’s sample, the people it holds for, and where it does not apply
Formula	Fitted in	Holds for	Not for
NWS wind chill (°F, mph)	A model of heat lost from the upwind side of a head-sized cylinder walking into the wind, in a steady state [4]; the wind reduced from 33 ft to 5 ft, face height, and no sun [1]	Air at or below 50 °F with wind above 3 mph, measured at 33 ft (10 m); people and animals	Warmer air or calmer wind; objects such as pipes or car radiators, which do not cool below the air temperature; bright sun, which the NWS says can raise the wind chill by 10 to 18 °F
Environment Canada formula 1 (°C, km/h)	The same model, with its own four-figure coefficients for °C and km/h	Air at or below 0 °C with wind of 5 km/h or more at 10 m	Wind under 5 km/h, where Environment Canada uses its light wind formula; air above 0 °C, where it shows no wind chill
Environment Canada risk levels	Freezing times for exposed skin, by the wind chill in whole °C	Planning time outdoors with skin exposed	Sustained wind over 50 km/h, where frostbite can come faster than the times; covered skin

Calculators and simulators

Sources

National Weather Service. Wind Chill Chart. weather.gov, read 25 October 2026. https://www.weather.gov/safety/cold-wind-chill-chart
National Weather Service. Wind Chill Chart (PDF), effective 1 November 2001, with its frostbite times. https://www.weather.gov/media/safety/windchillchart3.pdf
National Weather Service El Paso. Wind Chill, from its weather calculator notes (windChill.pdf). https://www.weather.gov/media/epz/wxcalc/windChill.pdf
Osczevski R, Bluestein M. The new wind chill equivalent temperature chart. Bulletin of the American Meteorological Society 2005;86(10):1453 to 1458. doi:10.1175/BAMS-86-10-1453
Environment and Climate Change Canada. Climate glossary: Wind Chill, formula 1. climate.weather.gc.ca. https://climate.weather.gc.ca/glossary_e.html
Government of Canada. Wind chill and the Wind Chill Index: risk levels and chart. canada.ca, modified 16 December 2025. https://www.canada.ca/en/services/environment/weather/severeweather/wind-chill-index.html