The cigars might mold, or your head could implode trying to draw through cigars swollen by that much moisture. I bought one from a local (crappy) shop with the humidity up over 80%, and I about busted a blood vessel trying to smoke it. Ended up throwing it out after a few minutes, just could not get it to draw at all.

I haven't had a humidifier in my humidor for a couple of months. The humidor is in the basement with the de humidifer running full blast trying to keep the humidity down. Agh the joys of summer in the south with no AC.