Server Maintenance: Patch 4.18 (Source)You can find all changes presumed to included into this patch in our complete 4.18 PBE cycle article !
On 10/09/2014, starting at 01:30 PDT, ranked queues will be disabled in preparation for patch 4.18. At 03:00 PDT, the servers will be shut down and all games currently in progress will end in a draw and stats will not be recorded. We estimate the battlegrounds will be unavailable for 6 hours.
League of Legends : Patch 4.18, servers maintenance
Servers will be unavailable tonight. Riot Games will deploy the new 4.18 patch on the live servers.