Wind Chill Factor Calculator
Find out what the cold really feels like on exposed skin. Enter the air temperature and wind speed, and this wind chill factor calculator returns the “feels-like” wind chill temperature, your frostbite risk time, and whether conditions meet typical wind chill school closure thresholds – using the official National Weather Service formula.
Reviewed for accuracy: July 2026 · Formula source: NWS / Environment Canada 2001 Wind Chill Index
In Fahrenheit (must be 50 F or below)
In mph (must be above 3 mph)
Feels Like
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Low riskAir Temperature
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Wind Speed
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Wind Chill (Feels Like)
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Temperature Drop
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Wind Chill School Closure Check
What Is the Wind Chill Factor?
The wind chill factor is how cold the air actually feels on exposed skin once wind is taken into account. Wind strips away the thin layer of warm air your body maintains against your skin, so your body loses heat far faster than the thermometer alone suggests. That is why 15°F with a 25 mph wind feels like −2°F: the air temperature has not changed, but the rate of heat loss from your body has climbed sharply. This wind chill factor calculator converts any temperature-and-wind combination into a single feels-like number and tells you how quickly frostbite can set in.
One important clarification, since it drives a lot of confusion: wind chill only applies to people and animals, not objects. A car, a water pipe, or a plant will never get colder than the actual air temperature, no matter how hard the wind blows – wind simply cools those objects toward the air temperature faster. Only living tissue that generates its own heat experiences the wind chill effect.
The Wind Chill Formula (NWS 2001)
This calculator uses the official wind chill temperature index adopted by the U.S. National Weather Service and Environment Canada in 2001. It replaced the older 1945 Siple-Passel formula after clinical trials in a refrigerated wind tunnel in Toronto measured real heat loss from human faces. The formula is valid only when the air temperature is 50°F (10°C) or below and wind speed is above 3 mph (about 5 km/h) – outside that range, wind chill is not meaningful.
WC = 35.74 + 0.6215T − 35.75(V0.16) + 0.4275T(V0.16)
Metric (°C, km/h):
WC = 13.12 + 0.6215T − 11.37(V0.16) + 0.3965T(V0.16)
Where T = air temperature and V = wind speed.
As a pharmacist who has spent years writing about cold-weather health and exposure risk, I want to underline why this matters beyond a “feels like” number on a weather app: wind chill is a clinical risk indicator. It predicts how fast peripheral tissue – fingers, toes, ears, nose, cheeks – reaches the freezing point. The colder the wind chill, the shorter the safe exposure window, which is exactly what the frostbite table below quantifies.
Wind Chill Frostbite Risk Chart
Frostbite risk depends on the wind chill temperature, not the air temperature alone. The National Weather Service defines these exposure thresholds for how quickly exposed skin can freeze:
| Wind Chill Temperature | Frostbite Risk | Time to Frostbite (Exposed Skin) |
|---|---|---|
| Above 0°F (−18°C) | Low | Prolonged exposure needed |
| 0°F to −17°F (−18 to −27°C) | Increasing | About 30 minutes |
| −18°F to −36°F (−28 to −38°C) | High | 10 to 30 minutes |
| −37°F to −53°F (−38 to −47°C) | Very High | 5 to 10 minutes |
| −54°F (−48°C) and below | Extreme Danger | Under 5 minutes |
Children, older adults, and people with circulatory conditions such as Raynaud’s phenomenon, diabetes, or peripheral vascular disease reach frostbite faster than these averages suggest, because reduced peripheral circulation means less warm blood reaching the skin. Certain medications – notably beta-blockers, which reduce blood flow to the extremities – can also lower cold tolerance. If you take one and spend time outdoors in extreme cold, factor in a shorter safe window than the chart shows.
Wind Chill and School Closures: The Cold-Day Threshold
Wind chill is one of the two weather triggers – alongside snowfall – that most often closes schools or cancels buses, and in the coldest regions it is the dominant one. Many US Midwest districts and Canadian school boards have automatic cold-day cancellation policies tied directly to wind chill, independent of how much snow is on the ground.
| Wind Chill | Typical School Impact |
|---|---|
| Warmer than −15°F (−26°C) | Schools generally open; outdoor recess may be limited |
| −15°F to −24°F (−26 to −31°C) | Cold Weather Advisory range; some rural bus cancellations |
| −25°F to −34°F (−32 to −37°C) | Common closure / bus-cancellation threshold in many districts |
| −35°F (−37°C) and colder | Widespread closures; Extreme Cold Warning conditions |
Exact thresholds are set locally, so treat the wind chill school closure check in this calculator as a strong indicator, not an official ruling. To pair a wind chill reading with a full snow-based closure probability for your ZIP or Canadian city, use our companion tool below.
Wind Chill Factor Converter: °F and °C
This tool doubles as a wind chill factor converter. Toggle between Fahrenheit-and-mph and Celsius-and-km/h at the top, and the calculator applies the correct NWS equation for that unit system and returns a matching result. You can convert a US weather report into metric, or a Canadian forecast into imperial, without doing the math by hand. To convert manually: F = (C x 9/5) + 32 for temperature, and mph = km/h x 0.6214 for wind speed.
Wind Chill Factor Calculator FAQ
The wind chill factor formula is the NWS 2001 index: WC = 35.74 + 0.6215T – 35.75(V^0.16) + 0.4275T(V^0.16), where T is air temperature in Fahrenheit and V is wind speed in mph. A metric version uses different constants for Celsius and km/h. It is valid only when temperature is 50 F (10 C) or below and wind speed is above 3 mph, and it estimates how cold exposed skin actually feels.
Frostbite risk rises sharply once the wind chill drops below 0 F (-18 C), where exposed skin can freeze in about 30 minutes. Between -18 F and -36 F, frostbite can occur in 10 to 30 minutes; between -37 F and -53 F, in 5 to 10 minutes; and below -54 F, in under 5 minutes. Children, older adults, and people with circulatory conditions or on certain medications reach these points faster.
Many US Midwest districts and Canadian school boards close schools or cancel buses when wind chill reaches roughly -25 F to -35 F (-32 C to -37 C), though exact thresholds are set locally. Cold Weather Advisories often begin around -15 F to -24 F, and Extreme Cold Warnings near -35 F. These cold-day closures happen independently of snowfall, purely to protect children from frostbite at bus stops.
Wind chill only affects people and animals, not inanimate objects. A car engine or water pipe will never drop below the actual air temperature no matter how strong the wind – wind only makes objects cool toward that air temperature faster. Pets, however, do experience wind chill just as people do, so the same frostbite and hypothermia precautions apply to dogs and cats left outdoors.
Use this calculator as a wind chill factor converter by switching the unit toggle at the top; it applies the correct NWS equation and returns the result in your chosen units. To convert a temperature by hand, use F = (C x 9/5) + 32, or C = (F – 32) x 5/9. For wind speed, mph = km/h x 0.6214. The wind chill itself is not a simple conversion – it must be recalculated with the matching-unit formula.
Related Winter Calculators
Disclaimer: This wind chill factor calculator provides estimates for general planning and safety awareness using the official NWS 2001 wind chill index. Frostbite times assume exposed skin and vary with clothing, moisture, age, health, and medication. It is not medical advice. If you experience numbness, waxy or grayish skin, or confusion in the cold, seek shelter and medical care immediately. Official closure and cold-warning decisions rest with school districts, school boards, and the National Weather Service.