I don't see where you are. That's a huge difference! I have no a/c and our summers can be humid. Concrete spices happen, so buy those that compact easily in the smallest amounts possible. Yes, the stove thing makes a difference. If you live in Arizona, probably not as big a problem. I think they've found stuff in ancient digs in the desert that is still usable (OK, I'm exaggerating). Sometimes, though, the hardened spices aren't unusable, just break them up with a skewer and taste. My biggest offenders are those that come in sort of cardboard type containers (my very favorite Cavender's!), that are hard to open and don't seal well. Second offenders are rectangular tins (think Coleman's mustard and most Hungarian Paprikas). Although they get hard, they're usually usable, assuming they aren't old enough to vote.