What Is Wind Chill and How Is It Calculated?
Wind chill is the temperature the human body actually perceives when wind is combined with the air temperature — often called the "feels like" temperature in cold weather. Wind strips away the thin layer of warm air next to the skin, so the same thermometer reading feels colder as wind speed increases.
This calculator uses the NWS/Environment Canada wind chill formula, adopted by the U.S. National Weather Service in November 2001: WC = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16), where T is air temperature in °F and V is wind speed in mph. The formula replaced an older 1945 model and is based on modern research into how quickly human skin loses heat.
According to the National Weather Service, this formula is valid for air temperatures at or below 50°F (10°C) and wind speeds above 3 mph (4.8 kph); outside that range, wind has little meaningful cooling effect and wind chill is reported as the actual air temperature.
How to Use This Wind Chill Calculator
Enter the air temperature and wind speed and the wind chill updates instantly. Here's what each field means:
- Air Temperature: The actual thermometer reading, in Fahrenheit or Celsius. Switch units with the toggle.
- Wind Speed: The sustained wind speed, in mph or kph — check a local weather report or weather station for a live reading. Use sustained wind, not gusts, for the most accurate estimate.
This calculator works in both Fahrenheit/mph (US customary) and Celsius/kph (metric), converting internally to Fahrenheit and mph for the NWS formula and back to your selected units for display, so results are accurate for winter conditions worldwide.
What Your Wind Chill Result Means
The NWS ties frostbite risk directly to wind chill temperature. These estimates assume exposed, dry skin with no wind-blocking clothing or shelter.
| Category | Wind Chill Range (°F) | Frostbite Risk |
|---|---|---|
| No Unusual Risk | 32°F and above | Wind has little cooling effect |
| Low Risk | 0°F to 32°F | Dress warmly; no immediate danger |
| Frostbite in 30 Min | -24°F to -1°F | Exposed skin can freeze within 30 minutes |
| Frostbite in 10 Min | -44°F to -25°F | Exposed skin can freeze within 10 minutes |
| Frostbite in 5 Min or Less | -45°F and below | Extreme danger — frostbite in 5 minutes or less |
For example, an air temperature of 0°F (-18°C) with a 15 mph wind produces a wind chill of about -19°F — cold enough that exposed skin can develop frostbite in roughly 30 minutes, according to National Weather Service guidance.
Frequently Asked Questions
What wind chill is dangerous for frostbite?
According to the National Weather Service, a wind chill of 0°F (-18°C) or lower can cause frostbite on exposed skin within about 30 minutes, and wind chills below -25°F (-32°C) can cause frostbite in as little as 10 minutes.
How accurate is this wind chill calculator?
This calculator implements the official NWS/Environment Canada wind chill formula exactly, matching the values published on NWS wind chill charts. It assumes dry, exposed skin with no wind-blocking clothing, and is only meaningful for temperatures at or below 50°F (10°C) with wind above 3 mph — outside that range it reports the actual air temperature.
What is the difference between wind chill and temperature?
Air temperature is a direct thermometer reading, while wind chill adds the cooling effect of wind to estimate how cold the air actually feels on exposed skin. The two are equal only in calm air (3 mph or less); as wind speed rises, wind chill drops well below the actual temperature.
How do I stay safe when the wind chill is low?
Cover exposed skin, wear layered wind-resistant clothing, keep extremities (fingers, toes, ears, nose) insulated, and limit time outdoors when wind chill drops below 0°F. Check our Heat Index Calculator for the warm-weather equivalent of this "feels like" measurement.
