Wind Chill Calculator

Temperature and wind

How it works

The NWS formula (adopted in 2001 from wind-tunnel trials on human volunteers) in Fahrenheit is: WC = 35.74 + 0.6215T − 35.75 V^0.16 + 0.4275 T V^0.16, where T is the air temperature in °F and V the wind speed in mph at standard anemometer height. The Celsius version uses the same structure with metric constants: WC = 13.12 + 0.6215T − 11.37 V^0.16 + 0.3965 T V^0.16, with V in km/h. The V^0.16 curve is why the first 15 mph of wind do most of the damage and stronger winds add less and less.

Valid range: the formula is defined for temperatures at or below 50 °F (10 °C) and wind speeds above 3 mph (about 5 km/h). Outside that range this page still returns the arithmetic result but flags it as outside the formula's range — in calm air or warm weather, wind chill is not a meaningful number.

What it means: wind chill is an estimate of how cold it feels on exposed skin — it is general information for dressing and planning, not a medical measure. Inanimate objects cool to the air temperature, never below it, no matter the wind chill. The frostbite guide bands are the NWS chart's: around −18 °F (−28 °C) frostbite can occur in about 30 minutes, around −28 °F (−33 °C) in about 15 minutes, and around −48 °F (−44 °C) in about 5 minutes or less.

Frequently asked questions

What is the wind chill at 30 °F with a 20 mph wind? 17 °F — the worked example on this page, and it matches the NWS wind chill chart exactly.

Does wind chill affect my car or pipes? Wind makes them cool to air temperature faster, but they cannot go below the actual air temperature. A wind chill of −10 °F on a 25 °F night will not freeze a pipe rated for 25 °F air.

Why do different sources give slightly different numbers? Older charts used the pre-2001 formula, which produced much colder values. This page uses the current NWS formula and chart.