Server Maintenance: Patch 4.10 (Source)
On 06/18/2014, starting at 01:30 AM PST, ranked queues will be disabled in preparation for patch 4.10. At 03:00 AM PST, 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 4.10, servers maintenance
Servers will be unavailable tonight. Riot Games will deploy the new 4.10 patch on the live servers.