In your condo settings you should be able to change the outside time for your condo and there should also be a day-night cycle so you can set clocks to the day-night in game time. And then there needs to be light switches for all the rooms. (Also, in the alpha, the condos are way too dark… Just take note for next alpha update. I also found a glitch where you can fall beneath the world by flying against the wall behind the theater and arcade.)
-hiotewdew
Day-Night Cycle has already been confirmed as a feature.
Oh, sorry. I didn’t know.
Confirmed? Where? I remember touching upon this in my Weather suggestion and Zak did not confirm it, nor do I see it in the confirmed post.
I think they might have shown a demo of it during the first stream
It was shown off as a feature in one of the early streams during the Kickstarter.
I always thought day-and-night cycles have been confirmed from the beginning, as such a system has been planned in GMT Lobby 2.
It’s also seen several times in the Kickstarter trailer.
I actually hope they will add this to the Alpha soon. 
Alpha won’t be updated until they can get on Steam with the alpha. (They’ll probably send us a steam key that lets us download it)
They said they probably wont do WEATHER as in rain, because they’d have to like mess with the lightning and it would be too hard. I’m not sure if this applies to day/night though.
You can see their exact response to their position on Weather in the post I linked, actually, and it’s more up in the air. A feature shelved possibly for a later day.
I’m not a game developer, but I assume if you used baked lighting you cannot have a day/night cycle. This might mean a breakthrough for weather after all.