Wind Chill Calculator
How cold it actually feels when the wind is stripping heat off your skin.
Apparent temperature
Wind chill
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Temperature drop
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Frostbite risk
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Why wind matters
Your body warms a thin layer of air right against your skin. Without wind, that layer insulates you. With wind, that warm layer is constantly stripped away and replaced with cold air — you have to keep heating new air. Same temperature, faster heat loss.
The NWS 2001 formula
The current formula replaced an older one based on a 1940s experiment with water in cylinders (the new one calibrates against an actual human face exposed to wind in a chilled wind tunnel). Valid for temperatures ≤ 50°F and winds ≥ 3 mph; outside that, the air temperature is what you feel.
Frostbite thresholds
At wind chill below 0°F, frostbite to exposed skin becomes a real risk:
- −18 to −28°F: 30 minutes.
- −28 to −40°F: 10 minutes.
- −40 to −55°F: 5 minutes.
- Below −55°F: 2 minutes or less. Stay indoors.