I'm new to chickens. I have 12 chickens six are 5 weeks old and six are 7 weeks old. The coop is ready and they must go outside. They've outgrown their brooder and must go to the coop. I'm just worried because the weather is still chilly. It will be all the way down to 28° one night, and a few degrees higher most of the week before it starts warming up a little bit. I'm worried if the 5 week olds are too young and need a heat lamp. We built vents at the top of the walls off the ceilings for ventilation so any draft will be above them. But I'm wondering if I need a heat lamp for the 5 week olds and if it'll be safe to have an outdoor extension cord in the rain to run it. My husband was thinking it would be a good idea to also close off some of the vents to keep it warmer. The coop is 12 feet by 6 ft and 6+ ft tall, so I don't know how warm it will stay with their body heat since it's on the larger side.