I thought the trailers implied there was day & night cycles.
In one of the earlier trailers, I remember there being a "morning" sun riseing type deal.
*edit: just checked the PGW 2017 Teaser, 30sec into it, theres a night time scene.
About weather though... your right, they havnt shown a "rainy" day type thingy in trailers yet.
Necro-bump this 2020: http://gamrconnect.vgchartz.com/thread.php?id=229249
Bumb in 2021: http://gamrconnect.vgchartz.com/post.php?id=9047071