There’s an announcement stickied at the top of General Discussion…
Season 26 | The Fall of the Nephalem | Preview Blog
Season 26 will begin on April 15, at 5PM (PDT/CEST/KST) shortly after our next Diablo III update. Read on to learn more about the season theme and balance changes coming in Patch 2.7.3. We are expecting this update to be released on April 12.