The attic is no place for cards if you can't keep the temps below about 90 degrees and the humidity less than about 45%. With older cards that have no gloss, that's about the minimum level of climate to keep the cards from getting damage. If you have some cards with gloss (like Glossy parallels, Glossy Inserts or Send-In sets), drop those temps and humidity even lower. If you have nothing glossy in those boxes and are using no plastic sleeves, they might be okay without climate-control in southern CA. Those aren't the only things you have to think about when storing cards in the attic though. Weather happens above your house and hail or rain can get in at some point. The first thing they'll damage is the stuff in the attic. There are lots of things to consider when storing cards away for a long period of time.
NO PWE's EVER!!! PLZ PM me 1st before sending any offer. ONLY selling cards as of March 2024. No trades or purchases right now.
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Largest total PC card collections by Team, then Athlete (as of 3/22/24):
STL Cardinals (MLB) - 8810; Carolina Panthers - 2888; GB Packers - 1790+ cards
Mark Martin (NASCAR) - 2038 cards; Jimmie Johnson (NASCAR) - 1875 cards; Jeff Gordon (NASCAR) - 1594; Ricky Rudd (NASCAR) - 839; Ozzie Smith (MLB) - 707