I brought my three girls home when they were 6 to 12 weeks old and it snowed unexpectedly the next day. My coop is a rabbit hutch conversion, the front completely open hardware cloth, no insulation. In a pinch, I covered the coop with an old wool blanket for insulation and an ugly blue rain tarp went over that at night, when it snowed, or in high winds. Off and on for a month we continued to have wintery weather and they did great with this setup. For this winter I do plan to surround the coop in straw bales for insulation and a wind break. I'll probably keep using my blue tarp, too. I will use the straw as mulch in my garden in the springtime.