Ah, the first time worries of the incubation mamma (don't worry, we still all worry about our babies, smiling). I have read so many posts about people that have lost power for periods of time whilst incubating, the babies hatch anyways. Picture the inside temperature of an egg. That is pretty warm. Even with no heat in the incubator, that will take quite a time to cool down the entire guts of the egg. Yes, I have seen broody mammas, even in cool spring, get off the eggs for a long period of time. Those babies still hatch. You will see. I doubt if it will affect the hatch, perhaps by half a day, but don't sweat it, they will be just fine. There is such concern when first learning to incubate, and all the responses you will hear will point to things that will help you, we learn by others' experiences. It is a good thing to listen and ask questions, you are doing this. Good luck....you gonna have some beautiful little fuzzy butts, and you will watch them for hours. Also remember, and this is a hard one, a chick can take up to a day to get out of the egg, even after it has pipped that first hole....some get out within a very short time, others take longer, dependent on breed too. I remember my light brahmas were always the first to actually get out of the shell. I remember some that I thought would never get out, but do eventually. Some may pip and never emerge. Those are the weak ones that you should think about if you want weakness in the flock or not. I do not help chicks to break through the shell anymore. Too many have times have I done this, only to have a chick not do well and die anyways. I have a tough love with incubation of chicks. I do not help them out, if they are too weak to get out, they do not have a place in my life. Just me. Have fun, you gonna be a happy mamma soon. Have a most wonderful day, CynthiaM.