Wind chill applies to people and animals, not objects. Cover exposed skin, and take wind chill alerts seriously at about -20°F and below.
| Air temperature (°F) | 5 mph wind | 10 mph wind | 15 mph wind | 20 mph wind | 30 mph wind |
|---|---|---|---|---|---|
| 30 | 25 | 21 | 19 | 17 | 15 |
| 20 | 13 | 9 | 6 | 4 | 1 |
| 10 | 1 | -4 | -7 | -9 | -12 |
| 0 | -11 | -16 | -19 | -22 | -26 |
| -10 | -22 | -28 | -32 | -35 | -39 |
| -20 | -34 | -41 | -45 | -48 | -53 |
What wind chill is
The National Weather Service defines wind chill as a measure of how cold people and animals feel when outside, based on the rate of heat loss from exposed skin caused by wind and cold. Wind makes it feel colder but does not lower the actual air temperature, and wind chill applies only to people and animals.
The formula
Wind chill in degrees Fahrenheit equals 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16), where T is the air temperature in °F and V is the wind speed in mph. It is defined only for air temperatures at or below 50°F and wind speeds above 3 mph.
Example values
The table shows wind chill values computed from the NWS formula, rounded to the nearest degree. At 0°F with a 15 mph wind the NWS gives -19°F.
When it becomes dangerous
As a general rule the threshold for potentially dangerous wind chill is about -20°F and lower. The NWS example at 0°F with 15 mph winds, a wind chill of -19°F, says exposed skin can freeze in 30 minutes. Frostbite can develop only if the actual air temperature is below freezing.
Alert thresholds are local
Offices set their own criteria. NWS Rochester, New York, issues an Extreme Cold Warning when the apparent temperature is expected at or below -25°F and a Cold Weather Advisory between -15°F and -24°F. Other offices differ, so read the alert for your area.
Staying safe
See our guide to frostbite and hypothermia, and the winter storm and winter weather alerts for your area.
Check your own location
See current official alerts and the impact for your ZIP code.
Common questions
What is wind chill?
A measure of how cold people and animals feel outside, based on the rate of heat loss from exposed skin caused by wind and cold. It does not change the actual air temperature.
How is wind chill calculated?
The NWS formula is wind chill (°F) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16), where T is the air temperature in °F and V is the wind speed in mph. It is defined only for air temperatures at or below 50°F and wind speeds above 3 mph.
What is the wind chill effect?
Wind carries heat away from exposed skin faster than still air, so a cold day feels colder when it is windy. That is the wind chill effect. It does not lower the actual air temperature, and it applies to people and animals, not to objects such as a car engine or a water pipe.
Is there a wind chill calculator?
Yes. The National Weather Service Weather Prediction Center offers a wind chill calculator on weather.gov. You can also use the NWS formula above or read the value from the table on this page, which lists wind chill for air temperatures from 30°F to -20°F and winds of 5 to 30 mph.
What wind chill is dangerous?
As a general rule, about -20°F and lower, according to the NWS glossary. Alert thresholds are set locally: for example, the Rochester, New York, office issues an Extreme Cold Warning at -25°F or lower and a Cold Weather Advisory between -15°F and -24°F.
Sources
Reviewed by the Storm Incoming editorial team on October 27, 2026. Follow local emergency officials if their instructions differ.