Wind chill is how cold it feels on exposed skin when wind is factored in. Moving air strips away the thin warm layer next to the skin, increasing heat loss and making it feel colder than the thermometer reading.

Why does the formula require at least 3 mph of wind and 50 °F or below?

The standard wind chill equation is only defined and validated within that range. At higher temperatures or calmer winds it gives little or no meaningful chill effect, so it is not applied.

How quickly can frostbite occur?

It depends on the wind chill. Above 0 °F the risk is low, but as wind chill drops past −25 °F frostbite can set in within 10–30 minutes, and below about −35 °F in under 5 minutes on exposed skin.

Is wind chill the same as the actual temperature?

No. Wind chill describes the rate of heat loss from skin, not the true air temperature. Objects without skin (like a car radiator) will not cool below the actual air temperature due to wind chill.

Wind Chill Calculator

Temperature

°F

Wind Speed

mph

Wind Chill19.0°F

Frostbite RiskLow risk

The Wind Chill Calculator reports how cold the air actually feels on exposed skin once wind is taken into account, using the official North American wind chill formula. Enter the air temperature in Fahrenheit and the wind speed in miles per hour, and it returns the wind chill temperature plus an estimate of how quickly frostbite can set in. The formula is valid for temperatures at or below 50 °F and winds of at least 3 mph.

Formula

WC = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16

T: Air temperature in degrees Fahrenheit
V: Wind speed in miles per hour
WC: Wind chill ("feels like") temperature in °F

How it works

Enter the air temperature in °F (must be 50 °F or lower) and the wind speed in mph (must be 3 mph or greater).
The calculator applies the NWS/Environment Canada wind chill equation, which combines the temperature and the wind speed raised to the 0.16 power.
It rounds the wind chill to one decimal and maps it to a frostbite-risk band, from "Low risk" above 0 °F down to "Under 5 minutes" below −35 °F.

Worked examples

Air temperature 0 °F with a 20 mph wind.

V^0.16 = 20^0.16 ≈ 1.6438.
WC = 35.74 + 0.6215×0 − 35.75×1.6438 + 0.4275×0×1.6438 ≈ 35.74 − 58.77 ≈ −22.0.

Wind chill ≈ −22 °F, with frostbite possible in 10–30 minutes.

Air temperature 20 °F with a 15 mph wind.

V^0.16 = 15^0.16 ≈ 1.5790.
WC = 35.74 + 0.6215×20 − 35.75×1.5790 + 0.4275×20×1.5790 ≈ 6.2.

Wind chill ≈ 6.2 °F, which falls in the "Low risk" frostbite band.

Frequently asked questions

What is wind chill?: Wind chill is how cold it feels on exposed skin when wind is factored in. Moving air strips away the thin warm layer next to the skin, increasing heat loss and making it feel colder than the thermometer reading.
Why does the formula require at least 3 mph of wind and 50 °F or below?: The standard wind chill equation is only defined and validated within that range. At higher temperatures or calmer winds it gives little or no meaningful chill effect, so it is not applied.
How quickly can frostbite occur?: It depends on the wind chill. Above 0 °F the risk is low, but as wind chill drops past −25 °F frostbite can set in within 10–30 minutes, and below about −35 °F in under 5 minutes on exposed skin.
Is wind chill the same as the actual temperature?: No. Wind chill describes the rate of heat loss from skin, not the true air temperature. Objects without skin (like a car radiator) will not cool below the actual air temperature due to wind chill.

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