Heat Index Calculator
Calculate the heat index (feels like temperature) based on temperature and humidity.
0%50%100%
Heat Index
99.7°F
Hot
Extreme Caution
Heat exhaustion possible
Potential Health Risks
Heat crampsHeat exhaustion
Recommended Precautions
Limit sun exposure
Stay well hydrated
Seek shade when possible
Temperature Comparison
Actual temperature
90°F
Feels like
99.7°F
Humidity at 60%
Makes it feel 9.7° hotter
Heat Index Danger Zones
Extreme Danger125°F+ / 52°C+
Danger103-124°F / 39-51°C
Extreme Caution90-102°F / 32-39°C
Caution80-89°F / 27-31°C
What is Heat Index?
Heat index is the apparent temperature felt when humidity is combined with air temperature. High humidity prevents sweat from evaporating, reducing your body's ability to cool itself.
Why Humidity Matters
Your body cools itself through sweat evaporation. High humidity slows evaporation, making it harder to cool down and increasing heat-related illness risk.
Heat Safety Tips
Stay hydrated, wear light clothing, avoid peak sun hours, take breaks in shade or AC, and watch for signs of heat illness: dizziness, nausea, rapid heartbeat.