Wind Chill Calculator
How cold the wind makes it feel on your skin, and how quickly frostbite can set in, using the official US and Canadian wind chill index.
By Manzoor Ahmad, pharmacist turned web designer · Updated How is wind chill calculated?
WC = 35.74 + 0.6215T − 35.75V0.16 + 0.4275T·V0.16 (T in °F, V in mph), or 13.12 + 0.6215T − 11.37V0.16 + 0.3965T·V0.16 in °C and km/h. At 0 °F with a 15 mph wind it feels like −19 °F (−29 °C), cold enough for frostbite on exposed skin in about 30 minutes.
Wind chill chart (°F)
Air temperature down the side, wind speed in mph across the top. Darker cells mean faster frostbite.
| Air temp | 5 mph | 10 mph | 20 mph | 30 mph | 40 mph | 50 mph |
|---|---|---|---|---|---|---|
| 40 °F (4 °C) | 36 | 34 | 30 | 28 | 27 | 26 |
| 30 °F (-1 °C) | 25 | 21 | 17 | 15 | 13 | 12 |
| 20 °F (-7 °C) | 13 | 9 | 4 | 1 | -1 | -3 |
| 10 °F (-12 °C) | 1 | -4 | -9 | -12 | -15 | -17 |
| 0 °F (-18 °C) | -11 | -16 | -22 | -26 | -29 | -31 |
| -10 °F (-23 °C) | -22 | -28 | -35 | -39 | -43 | -45 |
| -20 °F (-29 °C) | -34 | -41 | -48 | -53 | -57 | -60 |
| -30 °F (-34 °C) | -46 | -53 | -61 | -67 | -71 | -74 |
Frostbite risk by wind chill
| Wind chill | Risk | Exposed skin can freeze in |
|---|---|---|
| 0 to −9 °C (32 to 16 °F) | Low | — |
| −10 to −27 °C (14 to −17 °F) | Moderate | Hypothermia risk if outside long |
| −28 to −39 °C (−18 to −38 °F) | High | 10 to 30 minutes |
| −40 to −47 °C (−40 to −53 °F) | Very high | 5 to 10 minutes |
| −48 to −54 °C (−54 to −65 °F) | Severe | 2 to 5 minutes |
| −55 °C and colder (−67 °F) | Extreme | Under 2 minutes |
Risk levels follow Environment and Climate Change Canada guidance. In summer, check the heat index instead.
Wind chill FAQs
Wind chill is how cold it feels on exposed skin when wind speeds up heat loss from the body. It is expressed as the air temperature that would cause the same rate of heat loss in calm conditions.
In °F and mph: WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16. In °C and km/h: WC = 13.12 + 0.6215T − 11.37V^0.16 + 0.3965T·V^0.16. Wind is measured at 10 m (33 ft) height.
About −19 °F (−29 °C). Exposed skin can get frostbite in roughly 30 minutes at that wind chill.
For air temperatures at or below 50 °F (10 °C) and wind speeds of at least 3 mph (4.8 km/h). Outside that range wind chill is not defined and the air temperature is used.
Environment Canada guidance: at wind chills of −28 to −39 °C, exposed skin can freeze in 10 to 30 minutes; −40 to −47 °C in 5 to 10 minutes; −48 to −54 °C in 2 to 5 minutes; and −55 °C or colder in under 2 minutes.
No. Wind chill affects how fast heat leaves a warm object, but nothing cools below the actual air temperature. Pipes won't freeze unless the air itself is below 0 °C (32 °F).
Yes. Dogs and cats lose heat faster in wind too, especially short-haired, small, young or old animals. Ears, paws and tails are at risk of frostbite.
Both are 'feels like' temperatures. Wind chill applies in cold, windy weather; the heat index applies in hot, humid weather.
The older Siple–Passel index (1945) overstated the chilling effect. The 2001 index, developed by the US and Canadian weather services, uses a human face model, skin heat transfer and wind at face height, giving more realistic values.
Numbness, white or grayish-yellow skin and a firm or waxy feel, usually on fingers, toes, ears, nose and cheeks. Warm the area gradually and seek medical care; do not rub it or use direct high heat.
Shivering, exhaustion, confusion, fumbling hands, slurred speech, memory loss and drowsiness. A body temperature below 95 °F (35 °C) is a medical emergency.
Bright sunshine can make it feel about 6–10 °C (10–18 °F) warmer than the wind chill value, which assumes night-time or cloudy conditions.
Sources
For information only. Frostbite times are approximate for healthy adults with dry skin; children, older adults and people with poor circulation are at higher risk. Seek medical care for suspected frostbite or hypothermia.