CalcWind Chill Calculator
Wind Chill Calculator.
Wind Chill Calculator: Understand the True Cold of Windy Days
The wind chill calculator computes the perceived temperature on exposed human skin based on the actual air temperature and wind speed. Developed jointly by the National Weather Service and Environment Canada in 2001, the current wind chill index replaced older models and provides more accurate frostbite risk assessment. Whether you are planning outdoor winter activities, dressing for your commute, or managing safety for outdoor workers, knowing the wind chill temperature helps you prepare for the true severity of cold conditions.
Wind Chill Formula (NWS/Environment Canada)
WCT = 35.74 + 0.6215T − 35.75(V0.16) + 0.4275T(V0.16)
Where T is the air temperature in degrees Fahrenheit and V is the wind speed in miles per hour. For metric units, the formula is: WCT (°C) = 13.12 + 0.6215T − 11.37(V0.16) + 0.3965T(V0.16), where T is in °C and V is in km/h. The exponent of 0.16 on wind speed was derived from extensive testing with human subjects and thermal mannequins in wind tunnels to model the actual rate of heat loss from exposed skin.
The wind chill formula is valid only for temperatures at or below 50°F (10°C) and wind speeds above 3 mph (4.8 km/h). Below 3 mph, the wind chill is considered equal to the actual temperature because the natural convection layer around the skin remains intact. The formula assumes a calm wind speed of 4 mph (6.4 km/h) as the baseline, which is why even a gentle breeze of 5 mph creates measurable wind chill.
Worked Examples
Example 1: Winter Storm Conditions
During a winter storm, the temperature is 10°F (−12°C) with a wind speed of 25 mph (40 km/h). What is the wind chill?
Calculation (US units): V0.16 = 250.16 = 1.671
WCT = 35.74 + 0.6215(10) − 35.75(1.671) + 0.4275(10)(1.671)
WCT = 35.74 + 6.215 − 59.74 + 7.14 = −10.6°F
Metric: WCT = 13.12 + 0.6215(−12) − 11.37(1.671) + 0.3965(−12)(1.671) = 13.12 − 7.46 − 18.99 − 7.95 = −21.3°C
A wind chill of approximately −11°F (−21°C) means exposed skin can develop frostbite in about 30 minutes. Anyone outdoors should cover all exposed skin with appropriate winter clothing including a hat, scarf, gloves, and a windproof outer layer. Even a small break in coverage can lead to cold injury at these temperatures.
Example 2: Bitter Cold with Light Wind
The actual temperature is −15°F (−26°C) with a light wind of 10 mph (16 km/h).
Calculation (US units): V0.16 = 100.16 = 1.445
WCT = 35.74 + 0.6215(−15) − 35.75(1.445) + 0.4275(−15)(1.445)
WCT = 35.74 − 9.32 − 51.66 − 9.26 = −34.5°F
A wind chill of −35°F (−37°C) is in the "danger" zone. Frostbite can develop on exposed skin in approximately 10 minutes. At this wind chill, even brief exposure can cause cold injury. Multiple layers of clothing, chemical hand warmers, and limiting time outdoors to essential trips only are strongly recommended. This is a common scenario in the northern plains states and Canadian prairies during Arctic air outbreaks.
Common Uses
- Dressing appropriately for outdoor winter activities by understanding how wind combines with temperature to affect warmth
- Assessing frostbite risk for runners, skiers, snowboarders, and winter sports enthusiasts before heading outdoors
- Managing outdoor worker safety for construction crews, utility workers, and delivery personnel in cold climates
- Planning school closures and activity cancellations based on wind chill thresholds established by local districts
- Preparing for winter commuting by checking wind chill alongside temperature and precipitation forecasts
- Educating children and outdoor enthusiasts about cold weather safety and the importance of covering exposed skin
Common Mistakes
- Believing wind chill lowers the actual temperature of the environment — wind chill only affects how quickly living things lose heat; the actual air temperature remains unchanged
- Applying the wind chill formula to temperatures above 50°F (10°C) — the model was not designed for warm conditions and the results are meaningless
- Assuming wind chill is the same for all objects — wind chill only applies to warm-blooded creatures; a car or building will not cool below the actual air temperature
- Using wind speed measured at ground level instead of the standard 33 feet (10 meters) height — wind speeds are typically higher at standard measurement height, and the formula accounts for this
- Ignoring the effect of moisture — wet skin or clothing dramatically increases heat loss and the risk of hypothermia even at mild wind chill levels
Pro Tip
The most dangerous combination for cold injury is wind plus moisture. Wet clothing can lose insulating effectiveness by up to 90%, and the thermal conductivity of water is 25 times greater than air. If you are outdoors and your clothing becomes wet from sweat or precipitation, seek shelter immediately — even a relatively mild wind chill of 20°F (−7°C) can cause hypothermia in wet clothing. Use the acronym COLD as a dressing guide: Clean your clothing (dirt reduces insulating loft), avoid Overheating (unzip and vent instead of removing layers to prevent sweat accumulation), choose Loose layers (trapped air insulates), and keep Dry (waterproof outer layer is essential). For extended outdoor exposure when the wind chill drops below −20°F (−29°C), carry chemical hand and foot warmers, check companions frequently for signs of frostbite (white, waxy patches on skin), and have an emergency shelter option available.
Frequently Asked Questions
Wind chill is what the temperature feels like on exposed human skin due to the combination of cold air and wind. It is always lower than the actual air temperature when wind is present. The wind removes heat from the body faster by carrying away the warm air layer that naturally surrounds the skin.
Frostbite can occur in as little as 30 minutes when the wind chill reaches −20°F (−29°C) with exposed skin. At −40°F (−40°C) wind chill, frostbite can develop in 10 minutes or less. At −60°F (−51°C) wind chill, frostbite can occur in as little as 5 minutes.
No, wind chill only affects living things that generate body heat. It does not lower the temperature of inanimate objects below the actual air temperature. However, wind will cause objects to reach the air temperature faster by increasing convective heat loss.
The wind chill formula is designed for conditions where wind significantly increases heat loss from the body. At temperatures above 50°F (10°C), the wind does not pose a risk of cold-related injury. The formula also becomes less accurate at higher temperatures.