Then, it doesn't matter if you open the lid. You can even take some water out if you need to. I just fill one of the wells, and it usually gets me up to mid 30's for incubation. That's here in Utah. I don't worry much about the humidity during incubation going much under or over the mid 30's for incubation. 55 USED to be the norm..but most are finding that mid 30's is best for incubation, then I like to lock down at 62 to 65.No we are just trying to regulate it before we try and put our eggs in.