What is wind chill?
Wind chill (or wind chill temperature, WCT) expresses how cold the air actually feels on exposed skin once moving air is taken into account. Wind strips away the thin insulating layer of warm air next to your body and accelerates heat loss, so a calm 0 °C day feels much colder when a stiff breeze is blowing. This calculator uses the standard metric (Environment Canada / US NWS) wind chill formula with temperature in degrees Celsius and wind speed in kilometres per hour.
How to use it
Enter the measured air temperature in °C and the wind speed in km/h, then read the "feels like" value. The calculator also shows the cooling effect — how many degrees colder it feels compared with the thermometer reading. The formula is intended for temperatures at or below 10 °C and wind speeds above roughly 4.8 km/h; outside that range the result is only an approximation.
The formula explained
$$T_{wc} = 13.12 + 0.6215\,\text{Temp} - 11.37\,\text{Wind}^{0.16} + 0.3965\,\text{Temp}\cdot\text{Wind}^{0.16}$$ Here \(T\) is air temperature (°C) and \(v\) is wind speed (km/h). The \(v^{0.16}\) term captures the non-linear way that increasing wind speed produces diminishing extra cooling — doubling the wind does not double the chill.
Worked example
Suppose \(T = -5\) °C and \(v = 20\) km/h. First \(v^{0.16} = 20^{0.16} \approx 1.6188\). Then $$T_{wc} = 13.12 + 0.6215(-5) - 11.37(1.6188) + 0.3965(-5)(1.6188) = 13.12 - 3.1075 - 18.406 - 3.209 \approx -11.6 \text{ °C}$$ So a −5 °C day with a 20 km/h wind feels like about −11.6 °C.
FAQ
Why does it feel colder than the thermometer? Wind speeds the loss of body heat, lowering your skin's effective temperature even though the air temperature is unchanged.
Can wind chill be warmer than the air temperature? No — for the conditions this formula is designed for, wind chill is always equal to or below the actual air temperature.
What if the wind is very light? Below about 4.8 km/h the formula loses accuracy and the feels-like temperature is essentially the air temperature.
