I use this in a Home Assistant Template helper so it's updated automatically when any of the source sensors update. This is based on the simplified formula documented by the BoM here: http://www.bom.gov.au/info/thermal_stress
Substitute your sensor names
- YOUR_TEMP_SENSOR - degrees C
- YOUR_HUMDITY_SENSOR - percentage
- YOUR_WIND_SPEED_SENSOR - km/h
{% set temp = states('sensor.YOUR_TEMP_SENSOR') | float %}
{% set humidity = states('sensor.YOUR_HUMIDITY_SENSOR') | float %}
{% set wind_speed = states('sensor.YOUR_WIND_SPEED_SENSOR') | float %}
{% set wvp = humidity / 100 * 6.105 * e**(17.27 * temp / (237.7 + temp)) %}
{{(temp + 0.33 * wvp - 0.70 * wind_speed * 0.277777777777778 - 4.00) | round(1)}}