Be sure that the eggs that you want hatch are under a Broody hens it's not normal for a hen just to set all the time but when they go broody you will know it there fluff their feathers out and fast and not want to get off the nest. The normal temperature for a chicken is around a hundred and five degrees a Broody hen can keep her eggs warm she'll get down only periodically to eat and drink and get right back on in the dead of winter I will bring my broody and her eggs in and put her in a crate so the babies don't have to hatch wet in the very cold but the mother will take care of them and keep them warm if it's not extreme cold. I am a breeder I use an incubator but would much rather have my hens hatch and raise the babies.