Weather Feels-Like, Heat Index & Wind Chill Calculator
Model apparent temperature, human sweat evaporation thresholds, frostbite timelines, and dew points using official NOAA Steadman equations.
1. Ambient Air Temperature
2. Relative Humidity (%)
Moisture Index3. Wind Speed
Convective Cooling109°F
90.0°F
Thermometer81.2°F
Oppressive / TropicalHeat Index
NOAA Steadman+19.0°F
Humidity ImpactFeels-Like Temperature Curve Across Humidity Levels
At Current Air Temp (90°F)Click "Run AI Climate & Travel Audit" to evaluate sweat evaporation limits, calculate exact hourly electrolyte hydration targets, and determine appropriate clothing fabric layers. 100% private to you—zero server access.
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The Wet-Bulb Boundary: Why 92°F with 85% Humidity is Far More Dangerous Than 110°F Dry Desert Heat
An investigation into evaporative latent cooling, boundary-layer wind chill physics, and travel packing safety.
The Physics of Evaporative Sweat Cooling
The human body cools itself by secreting sweat, which absorbs 2,260 Joules of heat per gram when evaporating into ambient air. In dry desert heat (105°F with 15% humidity), sweat evaporates instantaneously. In humid tropical climates (92°F with 85% humidity), the air is saturated with water vapor, preventing sweat evaporation and sending the Heat Index soaring to 118°F (48°C), causing dangerous internal core heat accumulation.
NOAA Heat Index Danger Thresholds & Exposure Limits
| Apparent Heat Index | Risk Category | Physical Health Hazard | Travel Action Plan |
|---|---|---|---|
| 80°F – 90°F (27°C – 32°C) | Caution | Fatigue possible with prolonged exposure and activity. | Standard hydration (0.5L water/hr). |
| 91°F – 103°F (33°C – 39°C) | Extreme Caution | Heat cramps and heat exhaustion possible. | Electrolyte replenishment, shade rest. |
| 104°F – 125°F (40°C – 51°C) | Danger | Heat exhaustion likely; heat stroke possible with activity. | Limit outdoor exertion to early morning. |
| 126°F+ (52°C+) | Extreme Danger | Heat stroke / sunstroke imminent. | Immediate air-conditioned shelter. |
Frequently Asked Questions (Thermal Biometeorology)
What is the difference between Heat Index and Wind Chill?
Heat Index calculates how hot it feels when relative humidity is combined with high air temperature (impeding sweat evaporation), valid above 80°F (27°C). Wind Chill calculates how cold it feels when wind speed strips the warm air boundary layer from exposed human skin, valid below 50°F (10°C) with winds over 3 mph.
How is the NOAA Steadman Heat Index calculated?
The National Oceanic and Atmospheric Administration (NOAA) uses the multi-variable Rothfusz and Steadman regression equation combining dry-bulb ambient temperature and relative humidity percentage to estimate apparent body heat stress.
What Dew Point temperature feels humid and uncomfortable?
Dew point is the absolute measure of atmospheric moisture. A dew point below 55°F is crisp and comfortable; 56°F to 64°F feels pleasant to sticky; 65°F to 69°F feels humid; and a dew point of 70°F+ (21°C+) feels oppressive and tropical.