I live in Central Florida and my three pet hens live in an open coop. There is a "window" type cut-out about 18 inches by 12 inches for ventilation and there is the doorway from the ramp that is about 2 feet by 12 inches. The rest of the roost/nest area is closed. The rest of the coop is open and it's just hardwire cloth. I got the chickens in March, so this will be my first winter with hens. At what point do I worry about them being cold?? I wonder if I should put some wood over their vent rectangle that I mentioned.... and maybe do the same with the hole at the bottom of their entry ramp. Like I said - both are just open holes now that lead into the coop that is just hardwire cloth. I know that I was freeeeeeeezing the other night because the temps were around 58 degrees and I was worried about the chickens, but I thought that maybe it wasn't cold for them. Any ideas at what temp I need to give them a sealed coop with no openings for cold air/breeze to blow in at night? I'll obviously let them out in the run in the daytime. When it gets down to the 50s at night? or the 40s? or the 30s? Here is a pic so you can kind of see the coop. The dark teal place with the nest boxes is the only enclosed area (but with the large open "window" and doorway leading out to the rest of the coop - not the run). Thanks!!!!!