Wind Chill & Heat Index Calculator
Calculate what the temperature really feels like with wind chill and heat index formulas. Includes danger zone warnings.
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Frequently Asked Questions
How does the Wind Chill & Heat Index Calculator work?
Wind chill uses the NWS formula: 35.74 + 0.6215T - 35.75V^0.16 + 0.4275TV^0.16 (where T is temperature in Fahrenheit and V is wind speed in mph). Heat index uses Rothfusz's regression equation with temperature and relative humidity inputs. Both are empirical formulas derived from human body heat-loss models. Results are compared against NWS danger thresholds (frostbite risk, heat stroke risk) for color-coded warnings.
What is wind chill?
Wind chill is the perceived temperature when wind makes it feel colder than the actual air temperature. Wind accelerates heat loss from exposed skin, so a 30F day with 20 mph wind can feel like 17F.
What is the heat index?
The heat index is the perceived temperature when humidity makes it feel hotter than the actual air temperature. High humidity prevents sweat from evaporating, reducing your body's ability to cool itself.
What are the danger zones?
Wind chill below -20F risks frostbite in 30 minutes. Heat index above 105F is dangerous with risk of heat stroke. The tool shows color-coded warnings when conditions reach hazardous levels.