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Calculate the feels-like wind chill index based on air temperature and wind speed, assess frostbite risks, and get safety recommendations.
NWS equation at temperature <=50°F and wind >3 mph. Personal frostbite-time bands were removed. The index is not an object temperature or a local weather advisory. Reference
Adjust parameters to see results
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Wind chill combines air temperature and wind speed into an index for how cold moving air can feel on exposed skin. It is not a second thermometer reading: the actual air temperature remains the temperature reported by the thermometer. The index is useful when comparing cold, breezy conditions because faster moving air can increase heat loss from skin.
Enter air temperature and wind speed in either Fahrenheit and miles per hour or Celsius and kilometers per hour. The calculation converts metric values to Fahrenheit and mph, applies the U.S. National Weather Service equation, converts the result back when metric mode is selected, and rounds the displayed answer to one decimal place.
WCT = 35.74 + 0.6215T − 35.75V0.16 + 0.4275T·V0.16
T is air temperature in °F; V is wind speed in mph. This equation is defined for air temperature at or below 50°F (10°C) and wind strictly above 3 mph (about 4.8 km/h).
For example, entering −10°C and 20 km/h gives about −17.8°C. This is a wind-chill index, not a forecast: the calculator uses the values you provide and does not retrieve weather observations.
Reference
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Select Metric for °C and km/h, or Imperial for °F and mph. Switching systems converts the current temperature and wind values.
Enter readings for the same place and time. Use the air temperature, not a wind-chill value from another forecast. The sliders can adjust temperature and wind speed; the number fields also accept direct entry.
A result appears when temperature is at or below 50°F (10°C) and wind is greater than 3 mph (about 4.8 km/h). At warmer temperatures or lower wind speeds, the tool shows a message instead of a result.
The result area shows wind chill alongside the air temperature and wind speed used. Copy an individual value if needed. Reset returns the inputs to 0° and 10 km/h in metric mode.
Use cases
See how the tool fits into real work and everyday tasks.
For a walk, commute, or outdoor event, enter the forecast air temperature and wind speed to compare the wind-chill index with the thermometer reading. Check the local forecast separately for current conditions and any official alert.
A crew lead can calculate an index from the same site and time readings when discussing cold conditions with a team. Use workplace procedures and local weather guidance for decisions about work; the number alone does not set a safe exposure duration.
Q&A
Find concise answers to common questions and confusing cases.
No. It is an index describing the effect of wind and cold on heat loss from exposed skin. It does not mean air, water, or an object has cooled to that value.
The NWS defines this wind-chill equation only when wind is strictly above 3 mph and air temperature is at or below 50°F. At or below the wind threshold, the calculator does not show an index.
No. The inputs are air temperature and wind speed. The NWS describes its model as assuming no impact from the sun, so sunny conditions may feel different from the calculated index.
No. This calculation is not a weather alert. U.S. National Weather Service cold-weather advisory and warning criteria are set locally; check the official forecast for your location.
Notes
Review scope, result limitations, and important precautions before use.
Wind chill does not predict an individual's frostbite time, establish a safe exposure duration, or account for clothing, shelter, sunlight, health, age, or changing weather. It is not a substitute for local forecasts, official warnings, workplace safety procedures, or personal judgment. The displayed result is available only within the equation's stated temperature and wind conditions.
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