Wind Chill Calculator
Calculate the wind chill temperature (feels-like temperature) based on air temperature and wind speed using the NWS formula. See also Heat Index Calculator and Dew Point Calculator.
What Is Wind Chill?
Wind chill is the perceived decrease in air temperature felt by the body due to the flow of air. When wind blows across exposed skin, it removes heat from the body faster than still air at the same temperature. The wind chill temperature tells you how cold it actually feels on your skin. For example, if the air temperature is 20 degrees F and the wind is blowing at 15 mph, the wind chill makes it feel like 6 degrees F on exposed skin.
Wind Chill Formula (NWS)
The National Weather Service (NWS) uses the following formula, developed in 2001, to calculate wind chill for temperatures at or below 50 degrees F and wind speeds above 3 mph:
Wind Chill (F) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)
Where:
T = Air temperature in degrees Fahrenheit
V = Wind speed in miles per hour
Example Calculation
T = 20 degrees F, V = 15 mph
WC = 35.74 + 0.6215(20) - 35.75(15^0.16) + 0.4275(20)(15^0.16)
WC = 35.74 + 12.43 - 35.75(1.644) + 0.4275(20)(1.644)
WC = 35.74 + 12.43 - 58.77 + 14.06
WC = 3.5 degrees F (approximately 6 degrees F with rounding)
Wind Chill Frostbite Risk Diagram
How to Prevent Frostbite
Frostbite occurs when skin and underlying tissues freeze due to prolonged exposure to cold temperatures and wind. Here are key prevention tips:
- Cover all exposed skin, especially fingers, toes, ears, and nose
- Wear multiple layers of loose-fitting, warm clothing
- Keep clothing dry — wet clothing increases heat loss dramatically
- Limit time outdoors when wind chill values drop below -18 degrees F
- Watch for signs: numbness, white or grayish-yellow skin, skin that feels unusually firm
- Stay hydrated and well-nourished — your body needs fuel to generate heat
Wind Chill Reference Chart (degrees F)
| Temp / Wind | 5 mph | 10 mph | 15 mph | 20 mph | 30 mph | 40 mph | 60 mph |
|---|---|---|---|---|---|---|---|
| 40 F | 36 | 34 | 32 | 30 | 28 | 27 | 25 |
| 30 F | 25 | 21 | 19 | 17 | 15 | 13 | 11 |
| 20 F | 13 | 9 | 6 | 4 | 1 | -1 | -4 |
| 10 F | 1 | -4 | -7 | -9 | -12 | -15 | -18 |
| 0 F | -11 | -16 | -19 | -22 | -26 | -29 | -33 |
| -5 F | -16 | -22 | -26 | -29 | -33 | -36 | -41 |
Values in red indicate extreme danger — frostbite possible in 10 minutes or less.
Frequently Asked Questions
What is the difference between wind chill and actual temperature?
Actual temperature is the measured air temperature. Wind chill is the perceived temperature on exposed skin when wind is factored in. Wind does not lower the actual temperature of objects below the air temperature, but it does make your body lose heat faster.
Can wind chill freeze water pipes?
Wind chill does not affect inanimate objects like pipes directly — they cannot cool below the actual air temperature. However, wind can cause pipes to reach the air temperature faster, so if the actual temperature is below freezing, wind accelerates the freezing process.
At what wind chill should I stay indoors?
The NWS issues Wind Chill Advisories when values reach -15 to -24 degrees F and Wind Chill Warnings at -25 degrees F or below. At these levels, frostbite can occur in as little as 10-30 minutes on exposed skin.
Why is the formula only valid below 50 degrees F?
Above 50 degrees F, wind actually has a cooling effect that most people find comfortable rather than dangerous. The formula was calibrated using human trials in cold conditions and is not meaningful at warmer temperatures.
Does humidity affect wind chill?
The current NWS wind chill formula does not account for humidity. However, wet skin loses heat faster than dry skin, so being wet in cold, windy conditions is significantly more dangerous than the wind chill value alone suggests.
How was the wind chill formula developed?
The current formula was developed in 2001 by the NWS and Environment Canada using clinical trials where volunteers walked on treadmills in a refrigerated wind tunnel. It replaced the older Siple-Passel formula from 1945 which tended to overestimate wind chill.
Is wind chill the same worldwide?
The US and Canada use the same formula (NWS/Environment Canada 2001 model). Other countries may use different formulas or the older Siple-Passel index. The metric version uses Celsius and km/h but produces equivalent results.