Everywhere I have used my camera/housing has been high in humidity and with air temps in the 80's to 90's and water temps in the mid 70's to high 80's. All I do is keep the housing out of the sun and put 1 or 2 dessicant packs in the housing. No air conditioning, no dry air...just install the packs and close the door. Mine has never fogged the least little bit while those around me with different/smaller housings have had fog issues.