I realize this post is over a year old, but it came up in my search for information on broad breasted turkeys and cold. However, it seems to me that this advise may be misguided, despite all the experience here. A google search using the query "how tolerant are broad breasted turkeys to cold" shows the following: "Broad-breasted turkeys are not very tolerant of cold and require significant shelter, dry bedding, and protection from wind and drafts to survive winter. They are sensitive to extreme temperatures, so providing a heated shelter with good ventilation and wide perches to keep their feet off the cold ground is crucial for their health and to prevent frostbite."
Okay, so google AI could be wrong, but I strongly suspect not all turkeys are created equal. I have had heritage turkeys that want to sleep outside in a tree even when it's icey and near zero temperatures, though I always redirect them. However, I've noticed my broad breasted turkey shivers all the time and it's only gotten down the 30s so far. Opensanctuary.org states this: Large breed turkeys are extra sensitive to temperatures. "In the winter, it’s important to provide their housing with a safe heating source and a bit of extra food if it gets below freezing. In the summer, large breed turkeys can experience heat stroke in hot temperatures. To avoid this, make sure that the turkeys have an area where they can cool down comfortably."
Moreover, research on just chickens and cold tolerance in general shows that they do get cold when it gets below 35 degrees, so perhaps BYC experts might want to update some of their info.