Humidity of course changes as the water evaporates, the temperature changes, and the relative humidity changes. If you are opening the incubator, or it’s not closed properly, that is an issue as well.
Humidity is about surface, not volume. Three inches of water deep is less humidity than three inches wide.

I’m thinking (ouch!!). That is all I have tonight. Of course, my late fiancé always said of StoneMountain, “you go to school in a snowsuit, and come home in a swimsuit!”

If it’s that bad, you might want to have a humidifier in the room.