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Wind chill calculator

Estimate NWS wind chill from air temperature and wind speed, in °C or °F and km/h or mph.

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Tool guide

Wind chill calculator: how it works

Practical information to understand the result and use this tool correctly.

About Wind chill calculator

Wind chill is not heat index. Heat index uses temperature and humidity in hot weather. This tool uses the NWS 2001 cold-wind formula.

The formula is 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16, with T in °F and V in mph. Celsius and km/h are converted first.

The formula applies only when air is at or below 50°F and wind is at least 3 mph. Otherwise the result equals the air temperature.

How to use it

  1. 1Enter air temperature and choose °C or °F.
  2. 2Enter wind speed and choose km/h or mph.
  3. 3Read wind chill in both units, the formula note, and the NWS frostbite band.
  4. 4Copy the summary, load a preset, or reset. Nothing is uploaded.

Frequently asked questions

What is 0°F at 15 mph?
The NWS formula gives about −19.4°F (−28.5°C). V^0.16 for 15 mph is about 1.542, so 35.74 − 35.75×1.542 ≈ −19.4.
What is 0°C at 20 km/h?
0°C is 32°F and 20 km/h is about 12.4 mph. The same formula gives about 22.6°F, or −5.2°C.
Why is calm wind or warm air unchanged?
Below 3 mph or above 50°F the NWS 2001 formula is outside its range, so wind chill equals air temperature. Zero wind is calm. A negative wind speed is rejected.
What happens with an empty field or NaN?
An empty temperature or wind, text, or a non-finite value blocks the result. Wind cannot be negative. Temperature is limited to −80 through 60 in the selected unit.