Heat Index Calculator
Find out how hot it really feels. Enter the air temperature and relative humidity to calculate the heat index (feels-like) temperature.
Calculates the "feels like" temperature considering humidity. Uses NOAA formula.
How It Works & Formula
The heat index combines air temperature and relative humidity using a polynomial approximation to estimate the perceived temperature on the body.
Frequently Asked Questions
What is the heat index?
The heat index is a feels-like temperature that reflects how hot it feels when humidity reduces the body ability to cool itself.
Why does humidity make it feel hotter?
High humidity slows sweat evaporation, which is the body primary cooling mechanism, making it feel hotter.
When is heat index dangerous?
A heat index above 40 degrees Celsius (104 Fahrenheit) increases the risk of heat exhaustion and heat stroke.