Wind Chill Calculator
Calculate the official National Weather Service wind chill temperature from air temperature and sustained wind speed.
How It's Calculated
Formula
WCT = 35.74 + 0.6215T - 35.75V^{0.16} + 0.4275TV^{0.16}This calculator uses the official U.S. National Weather Service wind chill formula, adopted jointly with Environment Canada in 2001. T is air temperature in degrees Fahrenheit and V is sustained wind speed in miles per hour. The formula and the NWS's published wind chill chart are only defined for air temperature at or below 50°F and wind speed at or above 3 mph — outside that range, wind has a negligible or undefined chilling effect at the temperatures involved, so this calculator reports wind chill as equal to the air temperature rather than extrapolating the formula beyond its supported range.
Worked Examples
0°F air temperature, 15 mph wind
- V^0.16 = 15^0.16 ≈ 1.5427
- WCT = 35.74 + 0.6215(0) - 35.75(1.5427) + 0.4275(0)(1.5427)
- WCT ≈ -19°F
35°F air temperature, 1 mph wind (below domain)
- Wind speed 1 mph is below the 3 mph domain threshold
- Wind chill reported as the air temperature: 35°F
Frequently Asked Questions
Why isn't the formula applied for very light wind?
The National Weather Service defines the wind chill formula and chart only for wind speeds of 3 mph or greater — below that, wind has a negligible chilling effect, so wind chill is reported as equal to the actual air temperature.
Why isn't the formula applied above 50°F?
The NWS wind chill chart only covers air temperatures at or below 50°F, since wind chill isn't a meaningful safety concern at higher temperatures. This calculator does not extrapolate the formula outside its officially supported range.
Where does this formula come from?
It's the official NWS/Environment Canada wind chill formula, adopted in 2001, based on skin heat-transfer modeling rather than the older, less accurate wind chill index used before then.