Question 1

What is wind chill?

Accepted Answer

Wind chill is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. Strong winds remove heat from the body faster than calm air, making it feel colder than the actual air temperature.

Question 2

What formula does this calculator use?

Accepted Answer

This tool uses the official 2001 NWS (National Weather Service) wind chill index formula: WC = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16), where T is air temperature in °F and V is wind speed in mph.

Question 3

When is the wind chill formula valid?

Accepted Answer

The NWS formula is valid for air temperatures at or below 50°F (10°C) and wind speeds above 3 mph (4.8 km/h). Outside this range, the calculator displays a notice that wind chill is not officially defined.

Question 4

How does wind chill affect frostbite risk?

Accepted Answer

Frostbite can occur in 30 minutes or less when wind chill is below -19°F (-28°C). At -40°F (-40°C) frostbite can happen in under 10 minutes. The calculator shows frostbite warning levels in the result.

About the formula

Frostbite risk reference