I am going to check with others but I'm thinking as cold as it is you'd be better off bringing them in as they hatch. they will take them back even as far out as 3 weeks old probably older. It would be better if you could leave them but at the temps your talking about I wouldn't risk it excited for you that your hearing peepsSorry just re read your post.."as they hatch" the talking egg has not pipped yet...so I will just keep watch for now and set up another brooder. Six inches of snow plus ice is wearing me down.