Quick answer
Wind chill combines air temperature and wind speed to estimate how cold it feels on exposed skin. Faster-moving air carries body heat away more quickly.
It is a heat-loss equivalent, not a new measurement of the air temperature.
Why wind makes cold feel colder
Your body warms a thin layer of air close to your skin. Moving air disrupts that layer and replaces it with colder air, increasing heat loss. That is why an exposed, windy platform can feel harsher than a sheltered street at the same temperature.
Clothing, shelter, wetness, and activity also affect your experience. Wind chill is a useful shared reference, but it cannot describe every person’s clothing or surroundings.
Common misunderstanding
- “Wind chill is the temperature my thermometer should show.” No: the thermometer measures air temperature, while wind chill expresses a cooling effect.
- “One number captures every cold-weather hazard.” It does not. Wet clothing, ice, snow, visibility, and distance from shelter also matter. Read the wider forecast and local warnings.
Simple example
At 20°F (about −7°C) with a 15 mph (24 km/h) wind, the NWS equation gives a wind chill of about 6°F (−14°C). The air is still 20°F. The lower number describes the stronger cooling effect on exposed skin.
20°F + 5 mph
Wind chill: about 13°F.
A light wind increases cooling.
20°F + 15 mph
Wind chill: about 6°F.
The air temperature is still 20°F.
20°F + 30 mph
Wind chill: about 1°F.
Stronger wind draws heat away faster.
Imagine walking from a sheltered courtyard onto a windy bridge. The air temperature may barely change, while the loss of shelter changes how quickly you cool. The forecast wind chill helps you anticipate that exposed part of the journey.
How wind chill is calculated
The US National Weather Service formula uses air temperature and wind speed to model cooling of an exposed face. Colder air and stronger wind generally produce a lower wind chill. You do not need the equation to use the result.
The NWS calculation is defined for air temperatures at or below 50°F (10°C) and wind speeds above 3 mph (about 5 km/h). It is not a warm-weather comfort formula.
See the formula and its units
Wind chill (°F) = 35.74 + 0.6215T − 35.75V0.16 + 0.4275TV0.16
T is air temperature in °F; V is wind speed in mph. Do not insert Celsius or km/h values into this version of the equation.
Why wind chill can change
Wind chill responds to temperature and wind. Your own exposure also depends on shelter and clothing.
Air temperature
Colder air generally produces a lower wind chill when wind speed stays the same.
Wind speed
Faster-moving air disrupts the warm layer near skin and increases heat loss.
Shelter and exposure
An open bridge can feel harsher than a courtyard. Wetness and clothing affect your experience.
Forecast methods
Apps may use different inputs, update times, or apparent-temperature calculations.
Air temperature versus “feels like”
Keep the actual temperature and wind chill separate. Wind chill alone does not make a dry object cool below the surrounding air temperature; wind can make it reach that temperature faster.
A weather app’s “feels like” label is broader than wind chill. Providers may use different apparent-temperature methods and inputs. SkyAndTime displays its weather provider’s apparent temperature, so it should not be assumed to be this exact NWS calculation in every condition. See also Heat Index for the hot-weather concept.
How to use a wind chill forecast
Plan for wind, shelter, and time outside—not just the daily high.
Check the hours
Use hourly conditions for the time you will actually be outside.
Choose shelter
Consider exposed routes and access to warmth. An isolated outing needs more preparation.
Stay warm and dry
Wear suitable layers and protect exposed skin. A wind-resistant outer layer can help.
Plan warm breaks
Shorten or change an outing as conditions worsen. Check Weather and official local cold alerts.
Cold risk: frostbite and hypothermia
Very low wind chills signal faster heat loss and greater concern for frostbite on exposed skin. Hypothermia is a dangerous fall in core body temperature; it is different from frostbite and can occur without freezing conditions, especially when a person becomes wet and chilled.
A chart’s exposure-time bands are not a guaranteed safe time for an individual. Follow official local cold alerts, limit exposure, and seek urgent help for suspected frostbite or hypothermia.
Frequently asked questions
Can wind chill freeze water when the air is above freezing?
Wind chill alone cannot lower an object below the air temperature. It can make the object cool faster, but the wind-chill number is not its final temperature.
Does wind chill apply in summer?
The NWS wind chill formula is intended for cold conditions: at or below 50°F (10°C), with wind above 3 mph. Other measures describe warm-weather comfort.
Why might two apps show different feels-like values?
They may use different weather inputs, update times, or apparent-temperature formulas. Compare the location, time, and definition before treating them as the same calculation.
Sources & further reading
Official educational references checked September 27, 2026. Examples are illustrative, not live forecasts.
