The current heat index is linear using the model currently utilized by the US Govt *https://www.weather.gov/ict/wbgt#:~:text=The%20Wet%20Bulb%20Globe%20Temperature,sun%20angle%2C%20and%20cloud%20cover. * https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
The current heat index is linear using the model currently utilized by the US Govt
*https://www.weather.gov/ict/wbgt#:~:text=The%20Wet%20Bulb%20Globe%20Temperature,sun%20angle%2C%20and%20cloud%20cover.