Using the Wunderground component, the sensors used to return friendly names that I’m assuming are part of the component. You can see examples of how the component is supposed to return data if you scroll to the bottom of the component page in my link.
For example, when you add weather_1d to the monitored_conditions, that is the 12 hour forecast for the daytime. In the HA front end, this shows the forecast icon, and lists the day of the week, then the forecast. Now instead of the day of the week, Sunday, it shows the actual name of the sensor: pws_weather_1d. This is less than ideal.
I just started working on adding Wunderground and also found that the day of the week wasn’t being displayed in the forecasts. I don’t see how you could do that with customization since weather_1d will be Wednesday if the current day is Tuesday but of course that will change each time this is run.
Hopefully the bug will be caught and fixed soon but in the mean time did I miss seeing a way to fix this with customization?