I didn't know either! Searching for "wego weather" shows this CLI: https://github.com/schachmat/wego

Reading the readme for chubin/wttr.in also clarifies what "wego" is:

> wttr.in uses wego for visualization and various data sources for weather forecast information.

"wego" in that sentence is also linked to schachmat/wego so seems to confirm is that one.