Hi Cathy and Rick. I'm in Kingman, AZ. We will be getting the storm tomorrow also. My newest group is 19 weeks now but if they were only 6 1/2 weeks old I would put up a heat lamp. I too tend to over heat lamp but my thing is put up the lamp and give them plenty of room those that need it will use it, and there are always a few who are stay right under the light.
My group was hatched in July and our nights in the summer get down in the seventies. I provided a heat lamp through the night through their 6th week. Our cold is a very dry cold which tends to make it feel colder then the temperature says-if that makes sense. Again, if they were my girls I definitely would provide a heat lamp.