Depends what kind of quail. Bobwhites are very hardy, and can even survive -40c. Corturnix could probably survive quite some cold, too. Don't leave them in one of those open wire cages. Just give them a couple hiding places in a larger pen. And, of course, the water will freeze pretty fast. They always need fresh drinking water. My bobwhites are always outside. There are about 20 in a 20ft x16ft flight pen. Here in Ontario, Canada temps easily drop to -30c. They are hardy. They like playing in the snow. I also have lots of hiding places and an enclosure in there to stay out of all wind and snow. HOPE THIS HELPS,
Barend