I ran across this "fake the weather" on iOS, released this year. I'm not sure if it's available with other platforms. Basically it is mimicking the weather clock, but you can go to a menu and change the data to whatever you like. There are some limitations... no humidity/real feel info, and for some reason you can't have low temperatures in the extended forecast. Still, it seems to be the only thing of its kind right now. I think the creator's intention was to trick people into believing the weather would be something different than it really is, but obviously for people who update fictional locations it could be used for that also.
The only option for time is a 24-hour clock. Here's my weather report
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