How Do You Calculate Wind Chill

Wind Chill Calculator

Use this calculator to determine the wind chill temperature based on the current air temperature and wind speed. Understanding wind chill is crucial for assessing the real feel of cold weather and taking appropriate precautions.

function calculateWindChill() { var airTemperatureInput = document.getElementById("airTemperature").value; var windSpeedInput = document.getElementById("windSpeed").value; var resultDiv = document.getElementById("windChillResult"); var T = parseFloat(airTemperatureInput); var V = parseFloat(windSpeedInput); if (isNaN(T) || isNaN(V)) { resultDiv.innerHTML = "Please enter valid numbers for both air temperature and wind speed."; return; } var windChill; // The NWS Wind Chill Index formula is valid for temperatures at or below 50°F and wind speeds above 3 mph. if (T 3) { windChill = 35.74 + (0.6215 * T) – (35.75 * Math.pow(V, 0.16)) + (0.4275 * T * Math.pow(V, 0.16)); resultDiv.innerHTML = "The Wind Chill Temperature is: " + windChill.toFixed(1) + "°F"; } else if (T > 50) { windChill = T; // If temperature is above 50°F, wind chill is considered to be the actual air temperature. resultDiv.innerHTML = "The Air Temperature is above 50°F. Wind chill is not a factor, so the 'feels like' temperature is the actual air temperature: " + windChill.toFixed(1) + "°F"; } else { // V <= 3 mph windChill = T; // If wind speed is 3 mph or less, wind chill is considered to be the actual air temperature. resultDiv.innerHTML = "The Wind Speed is 3 mph or less. Wind chill is not a significant factor, so the 'feels like' temperature is the actual air temperature: " + windChill.toFixed(1) + "°F"; } }

Understanding Wind Chill

Wind chill is a term used to describe how cold it feels outside when the wind is factored in. It's not an actual temperature, but rather an index that indicates the rate of heat loss from exposed skin due due to the combined effect of cold air and wind. The higher the wind speed, the faster heat is carried away from the body, making it feel colder than the thermometer indicates.

Why is Wind Chill Important?

Knowing the wind chill temperature is vital for personal safety, especially during cold weather. It helps individuals and organizations make informed decisions about outdoor activities, clothing choices, and precautions against cold-related injuries such as frostbite and hypothermia. A low wind chill value means a higher risk of these conditions, even if the actual air temperature isn't extremely low.

The Wind Chill Formula

The calculator above uses the current U.S. National Weather Service (NWS) Wind Chill Index formula, which was implemented in 2001. This formula is based on scientific research and takes into account heat transfer from the human face to the environment. The formula is:

WCT = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)

• WCT = Wind Chill Temperature (in degrees Fahrenheit)
• T = Air Temperature (in degrees Fahrenheit)
• V = Wind Speed (in miles per hour)

Conditions for Applicability

It's important to note that the NWS wind chill formula has specific conditions under which it is most accurate and applicable:

• Temperature: The formula is valid for air temperatures at or below 50°F (10°C). Above this temperature, wind chill is generally not considered a significant factor, and the 'feels like' temperature is typically the actual air temperature.
• Wind Speed: The formula is valid for wind speeds above 3 mph (4.8 km/h). At or below 3 mph, the wind's effect on heat loss from exposed skin is minimal, and the wind chill is considered to be the actual air temperature.

If the conditions fall outside these parameters, the calculator will indicate that wind chill is not a significant factor, and the 'feels like' temperature is simply the air temperature.

Examples of Wind Chill

Let's look at a few examples to illustrate how wind chill works:

• Example 1: If the air temperature is 20°F and the wind speed is 15 mph, the wind chill temperature is approximately 4°F. This means exposed skin will feel as if it's 4°F, significantly colder than the actual air temperature.
• Example 2: With an air temperature of 0°F and a wind speed of 10 mph, the wind chill drops to about -16°F. This is a dangerously cold 'feels like' temperature.
• Example 3: If the air temperature is 55°F and the wind speed is 20 mph, the wind chill is considered to be 55°F. Since the air temperature is above 50°F, the wind chill formula is not applied, and the 'feels like' temperature is the actual air temperature.
• Example 4: An air temperature of 10°F with a very light breeze of 2 mph also results in a wind chill of 10°F. Because the wind speed is 3 mph or less, the wind's effect is negligible.

Always dress in layers, cover exposed skin, and limit time outdoors when wind chill values are low to protect yourself from the cold.