https://www.gamespot.com/articles/fortnite-season-5-update-being-prepped-with-server/1100-6460325/

Fortnite Season 5 is on the way, and that means another big patch is incoming soon. The servers will go down for an indefinite amount of time, and once the staging is all finished the Season 5 changes will finally be revealed.

According to a tweet from Epic Games, the server downtime will begin tomorrow, July 12 at 4 AM ET / 1 AM PT / 8 AM GMT. In a linked Reddit thread, the team also notes that this patch will be larger than normal, and recommends checking to make sure your auto-update settings are on. Plus, be prepared for possible slow download speeds, and save any content you want from your existing replays.