Wind Chill Calculator

Wind chill is the perceived decrease in air temperature felt on exposed skin due to wind. Moving air strips heat from the body faster than still air, making it feel colder than the actual thermometer reading. This calculator uses the official formulas adopted by the US National Weather Service and Environment Canada.

NWS Wind Chill Formula (Fahrenheit, wind in mph), revised 2001:

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

The pre-2001 formula was based on 1940s Antarctic experiments measuring how fast water containers froze in wind. The 2001 revision used human-skin heat-transfer models and gives noticeably less extreme results: the old formula reported a 20°F / 25 mph wind as feeling like −10°F; the current one reports it as feeling like 4°F.

Environment Canada Formula (Celsius, wind in km/h):

WC = 13.12 + 0.6215T − 11.37(V^0.16) + 0.3965T(V^0.16)

What each variable means:

• T: the actual air temperature measured by a thermometer, in °F or °C.
• V: wind speed at face height (about 1.5 meters), in mph or km/h.
• WC: the resulting wind chill temperature, representing what it “feels like.”

Valid range: The formula is designed for temperatures at or below 50°F (10°C) and wind speeds above 3 mph (5 km/h). Above these thresholds, wind chill equals the air temperature.

Practical example (Imperial): Air temperature = 20°F, wind speed = 15 mph. V^0.16 = 15^0.16 = 1.534. WC = 35.74 + 0.6215(20) − 35.75(1.534) + 0.4275(20)(1.534) = 35.74 + 12.43 − 54.84 + 13.12 = 6.5°F. It feels almost 14 degrees colder than the actual temperature.

Practical example (Metric): Air temperature = −5°C, wind speed = 25 km/h. WC = 13.12 + 0.6215(−5) − 11.37(25^0.16) + 0.3965(−5)(25^0.16) = approximately −11.4°C.

Frostbite risk reference:

• Wind chill at or below 0°F (−18°C): frostbite possible in 30 minutes
• Wind chill at or below −18°F (−28°C): frostbite possible in 10 minutes
• Wind chill at or below −40°F/°C: frostbite possible in as little as 5 minutes

Tips: Cover all exposed skin when wind chill is below 0°F (−18°C). Fingers, toes, ears, and nose are most vulnerable. Dressing in layers traps insulating air and is more effective than a single thick layer. Wet skin loses heat even faster, so keep dry in cold windy conditions.

Wind chill quick reference (°F):

One catch worth knowing: wind chill applies only to bare skin and warm-blooded animals. Inanimate objects (pipes, car engines, water in a bucket) cool only to the actual air temperature; wind speeds up the cooling but doesn’t lower the final temperature. A pipe at 35°F in a 30 mph wind does not freeze, regardless of what the wind-chill number says.