Heat Index Calculator
Calculate heat index from temperature and humidity. See danger level and activity recommendations.
Heat Index
105°F
Danger
Actual Temp
95°F
Feels Like
105°F
Humidity
50%
Activity Recommendation
Heat cramps and heat exhaustion likely. Heatstroke possible. Avoid strenuous outdoor activities. Stay in air conditioning.
Danger Level Reference
| Below 80°F | Comfortable |
| 80-90°F | Caution |
| 91-103°F | Extreme Caution |
| 104-125°F | Danger |
| 126°F+ | Extreme Danger |
Heat Index at Various Humidity Levels
| 20% humidity | 91°F |
| 30% humidity | 94°F |
| 40% humidity | 99°F |
| 50% humidity | 105°F |
| 60% humidity | 113°F |
| 70% humidity | 123°F |
| 80% humidity | 134°F |
| 90% humidity | 147°F |
Heat index is calculated using the Rothfusz regression equation from the National Weather Service. Values assume shady conditions; direct sunlight can increase heat index by up to 15\u00B0F. Always take precautions in high heat and humidity.
Use the Heat Index Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.
Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.
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