@weatheraarvark and @jenkins007:
This morning I grabbed 3.0.1 from last Thursday's Time Machine backup. (I upgraded to 3.0.2 on Friday.) I deleted the active .plist file, rebooted, and stuck my archived .plist in the preference folder, rebooted again for good measure, and then launched WeatherCat 3.0.1
I initially thought it wasn't working, because I got the beachball and no progress showing in the progress bar. But after a few minutes, it finished downloading, and was working like normal.
By the way, I'd also tried deleting my .plist file completely, rebooting and running WeatherCat 3.0.2 as a new user, and it still locked on downloading data. So it wasn't a borked preference file.
Stu, Like Weatheraardvark, I also have a Fusion drive with the new file system on Mojave. Could there be something odd with that configuration?