๐ค๏ธ Weather
Heat Index Calculator
The heat index is what the temperature feels like once humidity is counted, because sweat cannot evaporate efficiently in moist air. Above a heat index of 103 ยฐF the risk of heat illness rises sharply even for people who are just standing around.
How it works
Air temperature
Relative humidity
Temperature unit
Heat index
Heat index
Above the actual temperature
Category
Precaution
Frequently asked questions
How do I use the Heat Index Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.