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Wind Chill Calculator

Calculate how cold the air actually feels using the National Weather Service's wind chill temperature formula.

Wind chill
6.2°F (-14.3°C)
Air temperature
-6.7°C
Wind speed
24.1 km/h

How it works

This uses the U.S. National Weather Service's wind chill temperature formula, adopted in 2001 after clinical research on how fast exposed skin loses heat: WCT = 35.74 + 0.6215T − 35.75·V^0.16 + 0.4275·T·V^0.16, where T is air temperature in °F and V is wind speed in mph — verified against the NWS's own published formula rather than relied on from memory.

The formula is only valid, and only meaningfully colder than the plain air temperature, for temperatures at or below 50°F with wind faster than 3 mph — outside that range, moving air doesn't measurably change how cold the air feels, so this calculator treats those conditions as out of scope rather than extrapolating a formula that was never fit to them.

Results are also shown in Celsius and km/h for readers who don't think in Fahrenheit and mph, but the calculation itself always runs in the units the NWS formula was fit to — the site's usual metric/imperial toggle isn't used here because temperature conversion is an offset-and-scale operation this site's shared unit-toggle plumbing doesn't support (the same limitation noted on this site's Speed of Sound calculator).

FAQ

Why can't I enter temperature in Celsius or wind speed in km/h directly?

The NWS formula's coefficients (35.74, 0.6215, and so on) were fit specifically to Fahrenheit and mph, so converting the inputs to Celsius or km/h first and running the same formula would give a wrong answer. The result is shown in both unit systems, but the calculation itself always uses °F and mph.

Why does the calculator reject temperatures above 50°F or wind under 3 mph?

The NWS formula was derived and validated only within that range. Above 50°F, or with very light wind, moving air doesn't strip heat from skin fast enough to produce a meaningful wind chill effect, so the formula isn't defined there rather than returning a number that looks precise but isn't backed by the underlying research.

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