Since the babies are all done developing in their eggs, the temperature drop won't affect that part. If they're "shrink wrapped --like it sounds, in their inner membranes, the air space will look larger and without a flat edge on the chick side, when you candle.
What the shrink-wrapping hinders is the chick's ability to move around to pip & zip the egg, and eventually, the chick's ability to get air to breath.
By day 20 or so in almost all chickens, the chicks will pip internally, allowing them to breathe the limited air inside the air space. Once they do that, they have about a 24-hour period to break through to the outside to get air, or they'll suffocate. Like being trapped in an elevator a long while:\\
If you candle & see a little pointy shadow in the air space, it's a beak & they've pipped internally. If the chick isn't tightly wrapped in membrane due to humidity loss ...depends on your outside climate too, at this point, it can pip, zip, and hatch. If you have eggs that are shrink-wrapped inside, which isn't too likely as long as you fill your water reservoirs when it's on, there is a way to help the little ones hatch, but it takes the right timing & waiting for the blood to be absorbed from the membrane vessels, and you can look up threads on this, if you want to try. I've done this quite a bit during my first hatches and it worked for me on 5 out of 5, but I can't explain how I did it, and there's some controversy over assisting a hatch this much or not. I did this out of guilt, but it doesn't mean people should do it.
Assuming you don't have this problem, just wait & have faith in their ability to survive unforeseen problems. Broody hens aren't constant either a lot of the time.
What the shrink-wrapping hinders is the chick's ability to move around to pip & zip the egg, and eventually, the chick's ability to get air to breath.
By day 20 or so in almost all chickens, the chicks will pip internally, allowing them to breathe the limited air inside the air space. Once they do that, they have about a 24-hour period to break through to the outside to get air, or they'll suffocate. Like being trapped in an elevator a long while:\\
If you candle & see a little pointy shadow in the air space, it's a beak & they've pipped internally. If the chick isn't tightly wrapped in membrane due to humidity loss ...depends on your outside climate too, at this point, it can pip, zip, and hatch. If you have eggs that are shrink-wrapped inside, which isn't too likely as long as you fill your water reservoirs when it's on, there is a way to help the little ones hatch, but it takes the right timing & waiting for the blood to be absorbed from the membrane vessels, and you can look up threads on this, if you want to try. I've done this quite a bit during my first hatches and it worked for me on 5 out of 5, but I can't explain how I did it, and there's some controversy over assisting a hatch this much or not. I did this out of guilt, but it doesn't mean people should do it.
Assuming you don't have this problem, just wait & have faith in their ability to survive unforeseen problems. Broody hens aren't constant either a lot of the time.