While a form of heat index was introduced in form of the wet-bulb-temperature, which is a helpful feature, it does not take into acoount the wind chill effect. As someone living in a windy coastal area I want to advocate for introducing such a feature. Windchill is the last reason I keep other weather apps on my phone. For everything else Windy is superior to other apps in my opinion.
So please consider adding this as this is a long standing request as you can see in this thread.