Wind Chill Calculator
Calculate the wind chill temperature using the NWS/Environment Canada 2001 formula based on air temperature and wind speed. Use it to assess frostbite risk and decide whether outdoor exposure is safe in cold weather.
Last updated: May 2026
Compare with similar
About this calculator
Wind chill measures how fast wind accelerates heat loss from exposed skin, expressed as the equivalent still-air temperature that would produce the same cooling effect. The formula used here is the joint US National Weather Service / Environment Canada model adopted November 2001, replacing the older 1945 Siple-Passel formula: WC = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16, where T is the air temperature in °F and V is the wind speed in mph (measured at the standard 33-foot anemometer height — wind speeds at face height are about 2/3 of this). The result is wind chill temperature in °F. The model is valid for T ≤ 50 °F and V ≥ 3 mph; outside those bounds, wind chill is not reported because wind does not measurably accelerate heat loss in warm air or in nearly still conditions. The 2001 formula was derived from wind-tunnel measurements on human volunteers and physiological heat-transfer modeling, making it more accurate than the older formula, which overstated cooling by 20–40% at extreme conditions. Edge cases and limitations: wind chill applies only to exposed warm skin, not to inanimate objects — a metal pipe in 20 °F air with 30 mph wind still cools only to 20 °F, just faster. Direct sun exposure can offset wind chill by 5–10 °F. Wet skin loses heat far faster than dry skin and is not captured by the formula. The model assumes a walking adult; stationary or recumbent individuals experience less cooling, while exercising individuals experience more. Frostbite risk thresholds: −18 °F WC (30 min), −32 °F WC (10 min), −48 °F WC (5 min).
How to use
Example 1 — typical winter cold front. T = 15 °F, V = 25 mph. Step 1: V^0.16 = 25^0.16. Using ln: ln(25) ≈ 3.2189, × 0.16 = 0.5150, exp(0.5150) ≈ 1.6736. Step 2: WC = 35.74 + 0.6215 × 15 − 35.75 × 1.6736 + 0.4275 × 15 × 1.6736 = 35.74 + 9.32 − 59.83 + 10.73 = −4.0 °F. So 15 °F with 25 mph wind feels like −4 °F. NWS: frostbite possible on exposed skin in 30 minutes or less. Verify against an NWS lookup table at the same inputs: −4 °F — matches. Example 2 — severe arctic blast. T = −15 °F, V = 35 mph. Step 1: V^0.16 = 35^0.16. ln(35) ≈ 3.5553, × 0.16 = 0.5689, exp(0.5689) ≈ 1.7665. Step 2: WC = 35.74 + 0.6215 × (−15) − 35.75 × 1.7665 + 0.4275 × (−15) × 1.7665 = 35.74 − 9.32 − 63.15 − 11.33 = −48.1 °F. Frostbite on exposed skin in 5 minutes or less. Verify by direction check: lower T and higher V should both reduce WC, which they do here vs. example 1.
Frequently asked questions
How is the 2001 wind chill formula different from the older Siple-Passel model?
The original 1945 Siple-Passel formula was developed by US Antarctic researchers Paul Siple and Charles Passel using cooling rates of small plastic cylinders of water in Antarctic winds — not human skin. It overstated wind chill by 20–40% at extreme conditions, producing dramatic but inaccurate numbers that the public and emergency services found alarmist. The 2001 NWS/Environment Canada model was developed from controlled wind-tunnel experiments on twelve human subjects with face-mounted heat-flux sensors, plus a thermophysiological model of heat transfer through skin. It produces wind chill values closer to actual perceived cooling on a clean-shaven, sweat-free face during walking exercise. The new formula uses a lower exponent (0.16 instead of 0.5) on wind speed and a different intercept structure, yielding less extreme but more accurate values.
At what wind chill temperatures does frostbite become a serious risk?
The NWS publishes frostbite-time thresholds based on the 2001 formula. At −18 °F wind chill, frostbite can occur on exposed skin within 30 minutes; at −32 °F, within 10 minutes; at −48 °F, within 5 minutes; and at −60 °F, within about 1 minute. These times apply to typical adults with healthy circulation. Children, elderly individuals, smokers, and people with circulatory conditions face notably shorter onset times. The NWS issues Wind Chill Advisories at −15 °F to −24 °F and Wind Chill Warnings at −25 °F or colder. Outdoor workers in those conditions should follow OSHA cold-stress guidance: limit exposure, dress in layers with windproof outer shells, cover all exposed skin, and monitor for early signs like white or waxy skin patches, numbness, and tingling.
Why does wind chill apply only to warm skin and not to objects like pipes or cars?
Wind chill measures the rate of heat loss from a warm body to colder surrounding air. An inanimate object can only cool to the actual ambient air temperature, regardless of wind — the wind just makes the cooling happen faster. Once the object equilibrates with the air temperature, wind has no further effect; the wind cannot make the air colder than it actually is. This is why a water pipe will freeze only if the air temperature drops below 32 °F (its freezing point), regardless of whether wind chill makes the wind feel like −20 °F. Antifreeze, lubricants, and battery ratings are specified to actual air temperature, not wind chill. The same applies to plants: they care about the actual temperature, not the wind chill value.
What are common mistakes when interpreting wind chill?
The most frequent mistake is using wind chill to predict freezing of objects (pipes, plants, car fluids), which only respond to actual air temperature. Another error is applying the formula above 50 °F or below 3 mph wind, where it is not valid — the NWS does not report wind chill in those conditions because there is no physiological cooling effect to model. People also conflate wind chill with overall cold-weather discomfort, ignoring that wet clothing, low ground temperature, and direct precipitation can be more dangerous than wind alone. The formula assumes a moving (walking) subject; stationary individuals experience less wind chill, while running or cycling can effectively increase it. Finally, dressing for the wind chill (e.g., wearing minus-30 gear because WC is −30) is correct, but wearing only that gear and standing in 20 mph wind while the actual temperature is 25 °F can lead to overheating during exertion.
When should I NOT use this calculator?
Do not use wind chill for air temperatures above 50 °F or wind speeds below 3 mph — the formula is undefined in those ranges and gives misleading results. It is not the right tool for predicting how cold pipes, cars, or pets will get; those scenarios depend on actual air temperature and exposure time. Avoid it for marine or aviation contexts where wind speed is measured differently (knots, m/s) and where additional factors (wind chill at altitude, water-spray cooling) dominate — those need specialized cold-stress models. Wet-cold conditions (sleet, rain, sweat) drastically accelerate heat loss in ways the formula does not capture; in those cases, use the Australian wet-cold model or simply assume frostbite risk one category higher than the formula reports. For occupational decisions (OSHA, military), the WBGT-cold or similar wet-bulb-based models may be more conservative. Finally, for non-US users, check whether your national weather service uses the same 2001 formula — some still publish the older Siple-Passel values.