I definitely second that Turk Raphael. My first broody this year hatched during temps in the 30-40's. They were outside within a few days of hatch...because mama took them there. There were out with frost, rain, and wind. They learned chicken things far earlier and better than my store bought chicks that were a month older! A good broody is worth more than all the fancy equipment combined in my opinion! I think we sometimes tend to forget they have natural instincts...we are the ones that treat them like pets. True, I very much enjoy caring for and spoiling my chickens, but I believe they know better than I do what they need to survive and thrive.I'll say this and let it be my finish on the subject. Our chickens are free-ranged, protected by a dog during the day and locked up tight at night. I will give one example, a first time broody set on 6 eggs but only two hatched, for whatever reasons. On the 4th day, the hen had them outside in cold rain-blowing weather and it was almost cold enough to snow. I figured nature would take it's course and it did. When the chicks got a bit uncomfortable, they would run up under momma's skirt for a while then back out to pick and play.
Some will say the fact that these were White Chanteclers made the difference in their abilities to withstand the weather but I totally discount the breed. It was the hen's ability to care for her chicks. They ate from the layer feed and every other place they could find a bug, seed or something to gulp. By three weeks, they were eating a few BOSS and they were well protected from all comers that dared challenge them. They're weaned now but still hang with mom a bit but they have learned the 'pecking order' because mom quit defending them about 3 weeks ago and they roost together on their own, on a low rung. This is just one of several examples. If I have to treat brooded chicks like incubator chicks, I can't see the point. The only difference they were treated was worming with a substance more gentle for all the youngsters as they came of age and the next time, they will be wormed like the adults. Everyone dusts in Sevin-5% and are bug free.
Good luck with your chicks.