Do you mean the humidity outside? I just make sure their outdoor habitats have some areas with shale on the ground rather than plants and dirt. Gives them some dry zones to seek out. The sun bakes out the habitat pretty good during these hot summer months. I hose down the habitats a couple times a day, but I leave about 1/3 of the habitat dry.
Thats makes me feel better. Ive been a little concerned about issues popping up due to that. Mainly respiratory.