Weather tools
Standard Heat Index
Calculates the heat index, also known as the apparent temperature, which reflects how hot it feels to the human body when relative humidity is factored in with the actual air temperature.
Before you use this tool
Use this if
- Calculates the heat index, also known as the apparent temperature, which reflects how hot it feels to the human body when relative humidity is factored in with the actual air temperature.
- You want a calculation that exposes its formula: Heat Index = -42.379 + (2.04901523 × T) + (10.14333127 × RH) - (0.22475541 × T × RH) - (6.83783 × 10^-3 × T^2) - (5.481717 × 10^-2 × RH^2) + (1.22874 × 10^-3 × T^2 × RH) + (8.5282 × 10^-4 × T × RH^2) - (1.99 × 10^-6 × T^2 × RH^2)
- You already have Temperature, Relative Humidity values to enter.
Skip this if
- You need an official emergency alert or life-safety instruction.
- You need a certified professional forecast instead of a calculator estimate.
When to use or skip it
Use this if
- Calculates the heat index, also known as the apparent temperature, which reflects how hot it feels to the human body when relative humidity is factored in with the actual air temperature.
- You want a calculation that exposes its formula: Heat Index = -42.379 + (2.04901523 × T) + (10.14333127 × RH) - (0.22475541 × T × RH) - (6.83783 × 10^-3 × T^2) - (5.481717 × 10^-2 × RH^2) + (1.22874 × 10^-3 × T^2 × RH) + (8.5282 × 10^-4 × T × RH^2) - (1.99 × 10^-6 × T^2 × RH^2)
- You already have Temperature, Relative Humidity values to enter.
Skip this if
- You need an official emergency alert or life-safety instruction.
- You need a certified professional forecast instead of a calculator estimate.