Topic: Indoor Weather - Winter vs Summer

[MaverickNH]

I had my Davis WeatherLink 6313 display set to Outdoor & Indoor Temperature and Heat Index in the Summer (using temp & humidity only, as I have no solar sensor).

I changed my Outdoor display to Temperature and Wind Chill this Winter, but left the Indoor with Temperature & Heat Index. I notice that the Indoor Heat Index is 5 +/-2 degrees lower than the Temperature. We have no humidifier in our forced hot water baseboard heating system.

Is that lower Winter “Feels Like” Indoor Heat Index, presumably due to the lower humidity, a validated relationship or just calculated?