Wind Chill Calculator

Calculate the NWS wind-chill temperature from air temperature and wind speed when the observations fall inside the equation’s stated scope.

Inputs and method

Enter air temperature and wind speed in any supported units. Exact conversions normalize the inputs to Fahrenheit and miles per hour. The NWS equation is:

WCT = 35.74 + 0.6215T - 35.75V^{0.16} + 0.4275TV^{0.16}

Here, T is air temperature in degrees Fahrenheit and V is wind speed in miles per hour. The calculation finds a value only when converted temperature is at or below 50°F and converted wind speed is above 3 mph. Exactly 50°F is included; exactly 3 mph is not.

The formula always runs in Fahrenheit and mph. Choosing Celsius or Kelvin changes only the displayed result, not the NWS model or its scope. Intermediate values retain full precision before whole-degree display rounding.

Interpreting the estimate

Wind chill is a human-face environmental index based on adults. The NWS model assumes no effect from sunshine and uses wind speed adjusted to an average height of 5 feet from standard 33-foot anemometer readings.

Assumptions and limits

The result applies to people and animals. It does not mean an inanimate object will cool below the actual air temperature. The page does not estimate an individual’s frostbite time, risk category, or medical outcome.

The calculator rejects unsupported units, invalid numeric values, negative wind, temperatures below absolute zero, converted temperatures above 50°F, and converted wind speeds at or below 3 mph. Its numeric input limits are -100°F and 200 mph; these are interface limits, not additional NWS validity claims.

Frequently asked questions

Do Celsius and Kelvin inputs use a different wind-chill model?

No. They are converted exactly to Fahrenheit before the applicability check and equation. The result is converted back only for display.

Why is there no value at 3 mph?

The NWS defines wind chill only for wind speeds above 3 mph. A value exactly equal to 3 mph is outside that scope.

Sources

Wind Chill Chart — National Weather Service — equation, applicability thresholds, and model assumptions.
SI Units: Temperature — NIST — exact temperature conversions and absolute zero.
SI Units: Length — NIST and NIST Guide to the SI, Chapter 8 — exact mile and time relationships used for wind-speed conversion.
NIST Handbook 44 (2026), Appendix C — international nautical mile and knot definitions.