Pokémon GO will eventually be able to showcase weather in real-time in the game, such as it being overcast. Developer Niantic also plans to have the day transition into the night gradually with an evening look. Both of these plans are intended as future updates. The developer has also reconfirmed its plan of hosting large events akin to Ingress Portals where players can meet and communicate. Full details of these new features have yet to be announced, but stay tuned for any updates.
Source: Serebii
Pokémon Blog 