Automotive paints and relative humidity. Say wut?

I just bought some primer and reducer from AUTO ZONE today and asked that very question ! Like some one at the Zone would know something. HA. But I have painted a few cars in my life , by no means a painter. Most turned out nice, last one I painted down here in FL in the heat and 98% humidity turned out rough with orange peel . Same with the primer I sprayed the other day. Rough and dry. Using regular Rust-Oleum reducer.