Board Thread:Questions and Answers/@comment-31628427-20170623194415/@comment-28905095-20170629181055

In a single-player game, the game clock usually continues where you left it, if I'm not mistaken. So no point in taking extended leaves from those kind of games.

And as explained, unless the chunks are loaded, they are most likely not affected by a thunderstorm. So I think you should be extremely unlucky for the thunderstorm to do some damage to your stuff. Still building roof and walls around the chests sounds like a good idea, as that would also stop mobs from coming close to them.