Wind Chill Calculator: How is Wind Chill Calculated?

Wind Chill Calculator

Calculate Wind Chill

Enter the air temperature and wind speed to find out how cold it feels. Understand how is wind chill calculated.

Air Temperature:

Wind Speed:

Wind Chill vs. Wind Speed

Chart showing how wind chill changes with wind speed at the entered temperature.

Understanding How is Wind Chill Calculated

What is Wind Chill?

Wind chill, often referred to as the “feels like” temperature, is a measure of the rate of heat loss from the human body due to the combined effects of low air temperature and wind speed. It’s not the actual air temperature but rather an indication of how cold it feels to exposed skin. The higher the wind speed at a given low temperature, the faster heat is drawn away from the body, making it feel colder. Knowing how is wind chill calculated helps in understanding the risk of cold-related injuries like frostbite and hypothermia.

It’s important to note that wind chill affects warm-blooded animals and humans but does not affect inanimate objects like cars or pipes to temperatures below the actual air temperature. However, it will cause them to cool down to the air temperature more quickly. Meteorologists and public health officials use the wind chill index to issue warnings during cold weather, helping people take appropriate precautions when going outdoors. Many people misunderstand wind chill, thinking it’s a different, lower temperature; it is, in fact, an index based on heat loss.

Wind Chill Formula and Mathematical Explanation

The current formula used in North America (since 2001) for calculating wind chill is:

Wind Chill (°F) = 35.74 + 0.6215*T - 35.75*(V^0.16) + 0.4275*T*(V^0.16)

Where:

T = Air Temperature in degrees Fahrenheit (°F)
V = Wind Speed in miles per hour (mph), measured at a standard height of 5 feet (average face height).

If the input is in Celsius and km/h, it’s first converted to Fahrenheit and mph for the formula, and the result can be converted back. The formula is officially valid for temperatures at or below 50°F (10°C) and wind speeds above 3 mph (4.8 km/h).

The formula for Celsius and km/h (after conversion within the calculation) is approximately:

Wind Chill (°C) = 13.12 + 0.6215*T_C - 11.37*(V_kmh^0.16) + 0.3965*T_C*(V_kmh^0.16)

However, it’s more accurate to convert T_C to T_F and V_kmh to V_mph, use the Fahrenheit formula, and convert the result back to Celsius.

Variables in the Wind Chill Formula
Variable	Meaning	Unit (for standard formula)	Typical Range for Formula Validity
T	Air Temperature	°F	≤ 50 °F
V	Wind Speed	mph	≥ 3 mph
Wind Chill	Calculated “feels like” temperature	°F or °C	Varies

Table showing the variables used in the standard wind chill formula.

Practical Examples (Real-World Use Cases)

Understanding how is wind chill calculated is best done with examples.

Example 1: A Cold, Breezy Day

Air Temperature (T): 20°F
Wind Speed (V): 15 mph

Using the formula: Wind Chill = 35.74 + 0.6215*(20) – 35.75*(15^0.16) + 0.4275*(20)*(15^0.16) ≈ 4.8°F. So, it feels like 4.8°F.

Example 2: Very Cold and Windy

Air Temperature (T): -10°F
Wind Speed (V): 30 mph

Using the formula: Wind Chill = 35.74 + 0.6215*(-10) – 35.75*(30^0.16) + 0.4275*(-10)*(30^0.16) ≈ -46.1°F. It feels extremely cold, like -46.1°F, with a high risk of frostbite.

How to Use This Wind Chill Calculator

Enter Air Temperature: Input the current air temperature into the “Air Temperature” field. Select the correct unit (°F or °C).
Enter Wind Speed: Input the current wind speed into the “Wind Speed” field. Select the correct unit (mph, km/h, m/s, or knots).
View Results: The calculator automatically updates and shows the calculated Wind Chill temperature in the results area, along with intermediate values. It also displays any warnings if the inputs are outside the standard range for the formula.
Interpret Results: The “Wind Chill” value is the “feels like” temperature. Pay attention to warnings about frostbite risk at very low wind chill values.
Use the Chart: The chart dynamically updates to show how wind chill varies with different wind speeds at the temperature you entered.

Knowing how is wind chill calculated helps you dress appropriately and take precautions in cold and windy weather. See our frostbite risk guide.

Key Factors That Affect Wind Chill Results

Air Temperature: The lower the air temperature, the lower the wind chill. This is the starting point for heat loss.
Wind Speed: Higher wind speeds increase the rate of heat loss from the body, resulting in a lower wind chill value. The formula shows wind speed is a significant factor.
Exposure: The formula assumes exposed skin. Covering skin reduces the effect of wind chill.
Sunlight: Bright sunshine can make it feel slightly warmer than the wind chill suggests, although the official formula doesn’t account for solar radiation.
Humidity: While not directly in the wind chill formula, humidity can affect how cold it feels, especially at temperatures near freezing. High humidity in cold weather can make it feel damper and colder. Explore our relative humidity calculator for more.
Physical Activity: Being active generates body heat, which can offset some of the heat loss due to wind chill.
Individual Factors: Body fat, age, and metabolism can influence how an individual perceives cold and is affected by wind chill.
Formula Limitations: The formula is most accurate for the conditions it was designed for (≤50°F, ≥3 mph). How is wind chill calculated outside these ranges is less standardized.

Frequently Asked Questions (FAQ)

Q1: Is wind chill the actual temperature?: A1: No, wind chill is not the actual air temperature. It’s an index that represents how cold it feels on exposed skin due to the combined effect of air temperature and wind speed. Inanimate objects will cool to the air temperature, not the wind chill temperature, but faster with wind.
Q2: At what wind chill temperature is there a risk of frostbite?: A2: Frostbite can occur more quickly at lower wind chill values. For example, at a wind chill of -20°F, frostbite can occur in about 30 minutes on exposed skin, while at -40°F, it can occur in 5-10 minutes. Our cold weather safety tips provide guidance.
Q3: Why was the wind chill formula updated in 2001?: A3: The formula was updated based on new research and technology, including experiments with human volunteers, to more accurately reflect how the human body loses heat in cold and windy conditions. It also standardized the wind speed measurement height.
Q4: Does wind chill affect pets?: A4: Yes, wind chill affects pets and other warm-blooded animals similarly to humans, increasing their rate of heat loss.
Q5: What should I do if the wind speed is below 3 mph or the temperature is above 50°F?: A5: The standard wind chill formula is not used under these conditions. If the wind is below 3 mph, the wind chill is generally considered to be the same as the air temperature. Above 50°F, the “heat index” becomes more relevant in warm weather. Knowing how is wind chill calculated helps understand these limits.
Q6: Can I get wind chill if it’s sunny?: A6: Yes, wind chill is determined by air temperature and wind speed, regardless of sunshine. However, direct sunlight can provide some warming effect to the body, making it feel less cold than the wind chill value might suggest, but the official index doesn’t account for this.
Q7: Does humidity affect wind chill?: A7: The standard wind chill formula does not include humidity. However, damp air can feel colder, and high humidity can accelerate heat loss in some conditions, though it’s not part of the official calculation of how is wind chill calculated.
Q8: Where is the wind speed measured for the formula?: A8: The formula uses wind speed measured at a standard height of 10 meters (33 feet), which is then adjusted to 5 feet (1.5 meters, average face height) for the calculation because that’s where human skin is typically most exposed.

Related Tools and Internal Resources

Heat Index Calculator: Understand how hot it feels during warm weather by considering humidity.
Temperature Converter: Easily convert between Fahrenheit, Celsius, and Kelvin.
Weather Safety Guides: Resources on staying safe in extreme weather conditions, including cold and heat.
Barometric Pressure Converter: Convert pressure units.