If you can check on them as night progresses to see if they come down off the roost to find a more sheltered location. When I had them roost in trees, they would often come down during the extreme cold events. The following nights they would either roost in a more protected location like provided by a conifer tree or move some distance to roost in a building. Some would hunker down in high weeds or even venture into dog house to sleep on dog. I will be checking a couple times through night, but windchill here not likely extreme enough to cause such a move.