Calculate Wind Chill

Result

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Enter temperature and wind speed, then click Calculate.

The thermometer says 25°F and the wind is ripping at 20 mph—so how cold does it actually feel on your face? That gap between dry air temperature and perceived cold is what sends people back for another layer or, worse, out underdressed for a job site walk-through. Wind chill is not just weather trivia; it drives frostbite timing and outdoor work decisions. Enter air temperature and wind speed, pick Fahrenheit/mph or Celsius/km/h, and this calculator returns the NWS wind chill index plus a frostbite risk note.

How to Use This Wind Chill Calculator

Choose unit mode. Select Fahrenheit (°F, mph) or Celsius (°C, km/h). Temperature and wind speed must use the paired units shown on the radio buttons.
Enter air temperature. Use the dry-bulb reading from a thermometer or weather feed—not wind chill already reported by a news outlet.
Enter wind speed. Must be at least 3 mph or 4.8 km/h. Below that threshold the official formula does not apply because calm air does not accelerate heat loss from skin the same way.
Click Calculate. The wind chill index appears in the result panel. A frostbite risk summary runs underneath, and step-by-step math expands below the card when you need to show work.

Summer counterpart on the other side of the calendar: the Heat Index Calculator handles hot, humid apparent temperature. For moisture-only questions without wind, see the Dew Point Calculator.

Wind Chill Formulas and Practical Applications

Wind chill models how quickly exposed skin loses heat when cold air and wind work together. It does not make the air colder than the thermometer reads—it makes your body lose heat faster, so the effective cooling feels like a lower still-air temperature. The National Weather Service (NWS) and Environment Canada use the same modern index equations implemented here.

For Fahrenheit and wind speed V in mph:

WC = 35.74 + 0.6215 × T − 35.75 × V^0.16 + 0.4275 × T × V^0.16

For Celsius and wind speed V in km/h:

WC = 13.12 + 0.6215 × T − 11.37 × V^0.16 + 0.3965 × T × V^0.16

Example: T = 30°F and V = 15 mph yields a wind chill near 19°F—your skin loses heat as if the air were that much colder in calm conditions. In my experience on winter construction sites, that 10-degree gap is exactly when glove changes and face covering stop being optional.

Frostbite risk bands

The result panel maps wind chill to exposure guidance. These are rules of thumb for exposed skin, not guarantees—wet skin, altitude, and clothing matter.

Above −18°F (−28°C): Low risk for brief exposure.
−18°F to −35°F (−28°C to −37°C): Frostbite possible in about 30 minutes on exposed skin.
−35°F to −60°F (−37°C to −51°C): Frostbite possible in about 10 minutes.
Below −60°F (−51°C): Frostbite possible in 5 minutes or less.

Frequently Asked Questions

Does wind chill affect cars, pipes, or water?

No. Wind chill applies to living tissue that generates heat. Wind helps inanimate objects cool down to the actual air temperature faster, but it cannot push them below that dry-bulb temperature.

Why is there a minimum wind speed?

The NWS formula is validated for winds of 3 mph (4.8 km/h) and above. In light or calm wind, perceived cold is close to the actual air temperature, so the index adds little value and the equation is not defined for use below that cutoff.

What is the risk of frostbite under high wind chills?

As wind chill drops, exposed skin freezes faster. Near −18°F (−28°C) wind chill, frostbite can begin in about 30 minutes. Below −35°F (−37°C), that window shrinks to roughly 10 minutes or less.

Is wind chill the same everywhere in the world?

Most North American forecasts use the 2001 NWS formula shown here. Some countries publish different "feels like" indices that also fold in humidity or solar radiation. Compare apples to apples when checking international weather apps.

Should I use wind chill or air temperature for dress decisions?

Use wind chill when you will be outside in the wind with skin exposed—commutes, sports, roof work. If you are fully sheltered from wind, dress for the actual air temperature instead.

Disclaimer. RapidRatio is informational only. It is not professional safety, medical, or meteorological advice. Extreme cold conditions represent real hazards; always dress warmly and consult local weather warnings.