I have a couple of barred rock pullets that insist on hanging out in the pen, instead of cooping up with the rest. Every single night I have to go get them in the coop after dark. Okay, we have an isolation coop/run inside the pen. In that our newest pullet, Emily, was confined. So night before last, the two barred rocks, and one of my buffs decided to roost on top of the isolation coop...showing solidarity, I suppose, with the lil Emily that had protested her confinement loudly, all day. It was a very muggy night, and hot, so, in sympathy, I allowed the three (buff hen and barred rock pullets) to remain, roosting on top of the isolation coop. Big mistake. The pen is every bit as secure as the coop. But the mistake is that the pen isn't waterproof. At 3:15 am, guess where I was. Out in a thunderstorm, cooping up the sillies that roosted on top of the isolation coop. I live in a remote, forested area. Lightening flashing, rain pouring, wind blowing wildly...all out thunderstorm. Myself, my trusty Trixie (pyrenees) and my 9mm, out in the weather, at least 100 yards down a steep hill, cooping chickens at 3:15. I wont make that mistake again, LOL. But I totally get obsessing over your birds. We work so hard to take good care of them, keep them safe...they are pets, not just chickens. But I'm sure your lil chickens will be fine. If they are feathered out, and have each other for warmth, and the coop is secure...they will be just fine.