Calculate the official NWS wind chill from air temperature and wind speed. Optional sunshine context is shown separately and does not reduce frostbite guidance.
Quick Scenarios:
Conditions
The NWS wind chill formula applies at 50°F (10°C) or below.
0°F to −19°F (−18°C to −28°C)
Low
Possible with prolonged exposure
−19°F to −35°F (−28°C to −37°C)
Moderate
About 30 minutes
−35°F to −60°F (−37°C to −51°C)
High
About 10 minutes
−60°F (−51°C) and below
Extreme
About 5 minutes
Based on NWS exposure guidance. This is an approximate planning estimate, not a medical timer. Protect exposed skin and follow local warnings; risk varies with moisture, clothing, gusts, exertion, circulation, and shelter.
The NWS wind chill formula evaluates °F and mph at the reference height. Velocity pressure is a basic approximation, not a structural design value. CLO values are illustrative clothing guidance.
Scientific Rigor & Meteorological Verification
Last verified: July 2026
This calculator implements the official 2001 National Weather Service (NWS) / NOAA Wind Chill Temperature (WCT) Index, developed by the Joint Action Group on Temperature Indices (JAG/TI) incorporating clinical trials and heat transfer modeling by Osczevski and Bluestein.
Academic & Meteorological Citations
NOAA / National Weather Service:NWS Wind Chill Temperature Index and Frostbite Threshold Guidance (2001). weather.gov
Osczevski, R., & Bluestein, M. (2005):The new wind chill equivalent temperature chart. Bulletin of the American Meteorological Society, 86(10), 1453-1458.
Environment and Climate Change Canada (ECCC):Wind Chill Hazards and Calculation Methodology.canada.ca
Important Safety Notice: Frostbite guidance is approximate and is not a medical timer. Actual risk varies with exposed skin, moisture, clothing, wind gusts, circulation, exertion, and shelter. Follow official local weather advisories and protect exposed skin immediately in dangerous cold.
Wind chill answers a simple but important question: how cold does it actually feel, once wind is factored in?
📋
Walk-through
How to Use This Calculator
3 steps▸
1
Enter air temperature and wind speed
Type in the current (or forecast) air temperature and sustained wind speed. Use the °F/°C and mph/km-h toggles next to each field to switch units — the calculator converts internally so the result stays accurate either way.
2
Read the feels-like temperature
The result card shows the wind chill — the temperature your exposed skin actually experiences given the combination of cold air and wind. The interpretation line below adds the frostbite risk tier for those conditions.
3
Check the Frostbite Risk and Units tabs
Switch to the Frostbite Risk tab to see where your current conditions fall on the NWS frostbite-time scale, or the Units tab to see your inputs and result converted between °F/mph and °C/km-h side by side.
T is air temperature in degrees Fahrenheit and V is wind speed in miles per hour, measured at the standard anemometer height of 5 feet (1.5 m). WC is the resulting wind chill temperature, also in °F. The National Weather Service adopted this formula in 2001, replacing an older 1945 formula, after cold-weather research on facial heat loss. It is only valid for T ≤ 50°F and V > 3 mph — outside that range, wind does not meaningfully change the perceived temperature, so no wind chill value is defined. Example: T = 20°F, V = 15 mph → WC = 35.74 + 0.6215(20) − 35.75(15^0.16) + 0.4275(20)(15^0.16) ≈ 6.2°F.
📖
Glossary
Key Terms Explained
6 terms▸
Wind ChillThe temperature the human body perceives on exposed skin when accounting for both air temperature and wind speed. Wind strips away the thin layer of warm air the body maintains near the skin, so moving air at a given temperature feels colder than still air at the same temperature.
Feels-Like TemperatureA general term for any adjusted temperature that reflects perceived rather than measured conditions. In cold weather this is the wind chill; in hot, humid weather the equivalent metric is the heat index.
Wind SpeedHow fast the air is moving, measured in miles per hour (mph) or kilometers per hour (km/h). The NWS wind chill formula uses sustained wind speed measured at 5 feet (1.5 m) above the ground — gusts are not used directly.
FrostbiteInjury to skin and underlying tissue caused by freezing, most common on exposed extremities like fingers, toes, nose, and ears. Frostbite risk increases sharply as wind chill drops, because cold, moving air pulls heat away from skin faster than still air at the same temperature.
NWS (National Weather Service)The U.S. federal agency responsible for weather forecasts and warnings, including the official wind chill formula and Wind Chill Chart this calculator implements. The current formula was adopted in 2001 based on updated cold-weather physiology research.
Apparent TemperatureAnother name for a perceived-temperature index that combines air temperature with another environmental factor — wind chill (temperature + wind) and heat index (temperature + humidity) are both apparent temperatures.
👥
Scenarios
Real-World Examples
3 worked examples▸
🥶
Morning Commute
Typical winter cold snap
Air temperature 20°FWind speed 15 mph
WC = 35.74 + 0.6215(20) − 35.75(15^0.16) + 0.4275(20)(15^0.16) ≈ 6.2°F. Even though the thermometer reads 20°F, a 15 mph wind makes it feel about 14 degrees colder — cold enough to warrant a hat and gloves, but frostbite risk from wind chill alone is still minimal at this level.
🧊
Overnight Arctic Blast
Frostbite-time warning
Air temperature −10°FWind speed 30 mph
WC ≈ −39°F, which falls in the calculator's High frostbite-risk band — exposed skin can develop frostbite in about 10 minutes at these conditions. This is the kind of reading that triggers NWS wind chill warnings and justifies covering all exposed skin before going outside.
☀️
Mild Afternoon
Outside the formula's valid range
Air temperature 55°FWind speed 15 mph
Because the temperature is above 50°F, the calculator reports the conditions as outside the NWS wind chill formula's valid range instead of a misleading number — wind doesn't meaningfully lower the feels-like temperature once the air itself is this mild.
Wind chill answers a simple but important question: how cold does it actually feel, once wind is factored in? Two days at the same thermometer reading can feel completely different depending on how hard the wind is blowing, and that difference matters for deciding what to wear, how long to stay outside, and when conditions turn dangerous.
Why Wind Makes Cold Air Feel Colder
▸
Skin naturally warms a thin boundary layer of air right against it, insulating the body slightly from the surrounding cold. Wind constantly strips that warmed layer away and replaces it with fresh cold air, forcing the body to keep re-heating a new boundary layer and losing heat faster in the process. The stronger the wind, the faster this heat loss happens — which is why 20°F with a 15 mph wind feels closer to 6°F on exposed skin, even though a thermometer would read 20°F either way.
The 2001 NWS Formula and Its Valid Range
▸
The National Weather Service's current wind chill formula, adopted in 2001, replaced an older 1945 version after research using volunteers walking on a treadmill in a wind tunnel measured facial cooling more precisely. The formula — WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16 — takes air temperature in °F and wind speed in mph. It's only meaningful when T is 50°F or below and wind is above 3 mph; above that temperature or in calm air, wind doesn't meaningfully change how cold the air feels, so the NWS doesn't publish wind chill values outside that range and this calculator flags those inputs instead of returning a number.
From Wind Chill to Frostbite Risk
▸
The NWS pairs its Wind Chill Chart with frostbite-time guidance: as wind chill drops further below freezing, the time it takes for frostbite to develop on exposed skin shrinks from roughly 30 minutes down to 10, then 5 minutes or less at extreme wind chill values. These bands are estimates for uncovered skin under typical conditions — actual risk also depends on how much skin is exposed, clothing and moisture, and physical exertion, so treat the Frostbite Risk tab as a planning guide rather than a precise medical timer, and check official NWS.gov advisories before extended outdoor exposure in dangerous cold.
❓
Questions
Frequently Asked Questions
6 questions▸
What is the wind chill formula?+
The National Weather Service's 2001 formula: WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, where T is air temperature in °F and V is wind speed in mph. This calculator applies it directly and converts to/from °C and km/h as needed.
What is the valid range for wind chill?+
The NWS formula only applies at air temperatures of 50°F (10°C) or below, with wind speeds above 3 mph (about 5 km/h). Above that temperature or in near-calm air, wind chill is not defined because wind doesn't meaningfully change the perceived temperature.
How does wind chill relate to frostbite?+
As wind chill drops further below freezing, the estimated time for frostbite to develop on exposed skin shrinks — from roughly 30 minutes in the calculator's Moderate band down to 10 minutes in the High band and about 5 minutes or less in the Extreme band. These are general estimates, not exact medical timers.
What units does the calculator use?+
Temperature accepts °F or °C, and wind speed accepts mph or km/h, toggled independently. Internally the calculator always converts to °F and mph — the NWS formula's native units — before applying the formula, then converts the result back to your selected display unit.
How is wind chill different from the actual air temperature?+
Air temperature is what a thermometer measures; wind chill is what exposed skin perceives once wind is factored in. Wind constantly strips away the thin layer of body-warmed air near the skin, so moving air at a given temperature feels colder than still air at that same temperature — the stronger the wind, the bigger the gap.
Why doesn't calm wind show a wind chill value?+
The NWS formula requires wind speed above 3 mph (about 5 km/h) because at calmer winds, air movement isn't strong enough to meaningfully strip away the body's warm boundary layer — the perceived temperature stays close to the actual air temperature, so no separate wind chill figure applies.
📄
Save & share
Get a branded PDF of your results
Download a one-page PDF of your numbers instantly. Add your email to also get our occasional calculator tips — no spam, unsubscribe anytime. Privacy.