Thanks, glad to be here!
This must have been a custom text window. At the bottom of the "Window" drop down menu, there is a list of available windows: 1 hr. Rain Rate, Daily Rain, External RH, External Temperature, Internal Temperature, Pressure, This Week, Weather Station Gauges, WeatherCat, Wind Direction, and Wind Speed. At one point in time, there was also a This Month option in the list.
In the "Tools" drop down menu, "Custom Text Menus", "This Week" shows at the bottom as a window that can be opened, or deleted. I believe, originally, "This Month" also appeared here and I must have accidentally deleted it. I don't know how, but it's gone.
Each of this widows summarizes the week/month accordingly, showing the lows, highs, and averages for temp., humidity, pressure, wind, rain, etc.