Wind Chill Calculator
Find out how cold it really feels outside based on air temperature and wind speed using the NWS Wind Chill formula.
Wind chill is calculated when temp is 50°F or below
Wind speed must be 3 mph or higher for wind chill calculation
Wind Chill Chart (°F)
How the same temperature feels at different wind speeds
| Temp \ Wind | 5 mph | 10 mph | 15 mph | 20 mph | 30 mph | 40 mph |
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Safety Recommendation
Enter values and calculate to see safety recommendations.
Understanding Wind Chill and Cold Weather Safety
Wind chill is a measure of how cold it actually feels on exposed skin when the wind is factored in. On a calm day at 20 degrees Fahrenheit, your skin loses heat at a certain rate. But add a 15 mph wind, and the rate of heat loss increases dramatically, making it feel like it is only 6 degrees. Understanding wind chill is essential for anyone who spends time outdoors during cold weather, from commuters and dog walkers to construction workers and winter sports enthusiasts.
How the NWS Wind Chill Formula Works
The current wind chill formula was adopted by the National Weather Service and Environment Canada in 2001, replacing an older model from the 1940s that was based on experiments measuring how quickly water froze in plastic containers on a high Antarctic rooftop. The new formula is based on modern heat transfer theory and was validated with human trial data involving subjects walking on a treadmill in a refrigerated wind tunnel at the Defence and Civil Institute of Environmental Medicine in Toronto.
The formula calculates wind chill as: WC = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16), where T is the air temperature in Fahrenheit and V is the wind speed in miles per hour. The formula is only valid when the temperature is at or below 50 degrees Fahrenheit and the wind speed is at or above 3 miles per hour. Below 3 mph, the wind has minimal effect on perceived temperature.
Frostbite Warning Signs
Frostbite occurs when skin tissue freezes, and it can happen much faster than most people realize. At a wind chill of negative 10 degrees Fahrenheit, exposed skin can develop frostbite in as little as 30 minutes. At negative 28 degrees, that window shrinks to just 10 minutes. The fingers, toes, nose, ears, and cheeks are the most vulnerable because they have high surface-area-to-volume ratios and are often the least protected.
The first sign of frostbite is frostnip, a numbness or tingling sensation accompanied by skin that turns red and then white or grayish-yellow. If you notice these symptoms, move indoors immediately and warm the affected area gently with body heat. Never rub frostbitten skin, as this can cause tissue damage. Severe frostbite involves deep tissue freezing and requires immediate medical attention.
Dressing for Extreme Cold
The key to staying warm in cold and windy conditions is layering. A proper three-layer system starts with a moisture-wicking base layer made of synthetic fabric or merino wool that pulls sweat away from your skin. The middle insulating layer, typically fleece or down, traps body heat in air pockets. The outer shell layer blocks wind and repels moisture. Cotton should be avoided as a base layer because it absorbs moisture and loses its insulating properties when wet, a dangerous combination in cold weather.
Extremities deserve extra attention. A warm hat is critical because significant heat escapes through an unprotected head. Insulated, waterproof gloves or mittens protect the hands, with mittens being warmer because the fingers share body heat. Thick wool or synthetic socks inside insulated, waterproof boots protect the feet. A balaclava or neck gaiter covers the exposed skin on the face and neck that is most vulnerable to wind chill.
Wind Chill vs. Actual Temperature
An important distinction is that wind chill describes how cold it feels to human skin, not the actual air temperature. A thermometer will still read the true air temperature regardless of wind speed. Water in a pipe will freeze at 32 degrees Fahrenheit whether the wind is calm or blowing at 40 mph. However, wind accelerates the rate at which objects and exposed skin cool toward the air temperature. This means that on a windy day, exposed skin reaches the danger zone for frostbite much faster, even though the endpoint temperature is the same. Wind chill is therefore a measure of danger to living tissue rather than a physical temperature measurement.