Wind Chill Calculator

Wind chill is a measure of the cooling effect of wind on exposed human skin. The current NWS wind chill formula, adopted in 2001, was developed based on advances in science, technology, and computer modeling, replacing the older Siple-Passel formula from 1945. The formula is: WC = 35.74 + 0.6215*T - 35.75*V^0.16 + 0.4275*T*V^0.16, where T is air temperature in Fahrenheit and V is wind speed in miles per hour. This formula is valid for temperatures at or below 50°F and wind speeds above 3 mph. The physics behind wind chill involves convective heat transfer. The human body warms a thin layer of air next to the skin. In calm conditions, this insulating layer reduces heat loss. Wind strips away this warm layer, increasing the rate of heat loss from the body. Wind chill has practical safety implications. At wind chills below -18°F, frostbite can occur on exposed skin within 30 minutes. Below -48°F, frostbite can develop in under 10 minutes. Below -65°F, frostbite can happen in under 5 minutes. It is important to note that wind chill is a perceived temperature for human skin. Objects like car engines and water pipes are not affected by wind chill because they cannot cool below the actual air temperature. However, wind does increase the rate at which objects cool to the ambient temperature. The wind chill index does not account for solar radiation. Sunny conditions can make the perceived temperature feel 10-18°F warmer than the calculated wind chill.