本日の日本時間19時よりPatch3.10を伴う6時間のメンテナンスが行われます。
(Rankedは17時30分で停止)
Summoners,

On 7/31/13, starting at 01:30 AM PST, ranked queues will be disabled in preparation for patch 3.10. 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.
http://na.leagueoflegends.com/board/showthread.php?t=3718452

パッチノートも翻訳しました
http://mobasoku.doorblog.jp/archives/30140026.html