Fireproof Archival Storage. No Ball Cubes.

[steve B]

In a house with a central air/heat system, it really shouldn't be a concern. Especially if it's modern, since adequate insulation helps prevent big temperature swings. So the ambient air when the safe gets loaded will be mostly right for storage, around 40% humidity is good for most things. (and 40 degrees F too, but that isn't really reasonable for most people)
As David said, just opening the door for a while now and then would give enough air transfer and opportunity to check on things.

Now in a house like mine that's 1880's, has no insulation, and only a couple window AC units, and can be 60 downstairs and 80 upstairs.... Yeah, for me it may not be a great choice. Fortunately, I don't have any autographed balls that are particularly expensive in my collection. (I only have maybe 5 total? ) *

*They're in a "fire resistant" card file cabinet.... Meaning someone built a cabinet to store 3x5 cards, and the space between the inner body and outer is filled with firebrick. But the drawers don't seal... So if there was a minor fire near it, stuff might be ok, but it wouldn't survive a major fire.
That cabinet is also damn heavy..