Wind chill is a measurement of the rate of heat loss from your body when you're exposed to low temperatures combined with wind. At the beginning of the 20th century, researchers in Antarctica developed the measurement to estimate the severity of local weather. By the 1960s, wind chill equivalent temperatures were a common feature of weather reports. The U.S. National Weather Service began providing wind chill calculation tables in the 1970s. The way wind chill factor is calculated has recently changed.
Measure wind speed with your anemometer. The National Weather Services uses a height of 5 feet from ground level for calculating wind chill. Record the wind speed.
Measure and record the current temperature at the location of your wind measurement with the thermometer.
Calculate the wind chill using the National Weather Service's new formula. Multiply the temperature by 0.6215 and then add 35.74. Subtract 35.75 multiplied by the wind speed calculated to the 0.16 power. Finally, add 0.4275 multiplied by temperature, multiplied by wind speed calculated to the 0.16 power. Your result is defined as T(wc), which equals the current local wind chill factor.
You can make your own anemometer and calculate wind speed and wind chill factor. However, simple calculator tools are available online from the National Weather Service and other sites, so if time is of the essence and you already know the wind speed and temperature at your location, using one of these tools is a simpler option.
The historic wind chill calculation formula was T(wc) = 0.81 times (3.71 multiplied by the square root of the wind speed plus 5.81 minus 0.25 multiplied by wind speed) times (temperature minus 91.4) plus 91.4. The National Weather Service decommissioned this formula and its associated charts because they overestimated weather severity by failing to take into account human motion and constant minimum levels of air movement.